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Re[6]: Kosmicheskii teleskop "Habbl"
8.08.2007 12:57 | Dmitrii Docenko
Hm. Nu, ya dumal, vy znaete, kak poluchayutsya spektry. Seichas ob'yasnyu.
Ob'ektiv teleskopa formiruet izobrazhenie uchastka neba na fokal'noi ploskosti. V prosteishem sluchae tam mozhet stoyat' fotoplastinka ili PZS-matrica, ili zhe eto izobrazhenie astronom mozhet razglyadyvat' cherez lupu, kotoraya v dannom sluchae nazyvaetsya okulyarom. Uglovoe razreshenie v ideal'nom sluchae opredelyaetsya difrakciei.
Vmesto etogo fokal'nuyu ploskost' mozhno zakryt' neprozrachnoi plastinoi, ostaviv v nei tol'ko nebol'shuyu dyrku (obychno ispol'zuetsya shel', no ee mozhno predstavit', kak summu nakih dyrok). Za etoi dyrkoi stavyat dispergiruyushii element (prizmy, difrakcionnyyu reshetky, eshelett), posle kotorogo svet razdelyaetsya na spektr. Opticheskaya sistema snova sobiraet etot svet na sleduyushei fokal'noi ploskosti. Takim obrazom, iz tochki poluchetsya 1-mernyi spektr. Iz sheli, sootvetstvenno, poluchaetsya 2-mernyi spektr (napravlenie dispersii dolzhno byt' perpendikulyarno sheli).
Razmer sheli (v uglovyh edinicah) ne imeet smysla delat' men'she, chem razreshenie teleskopa - inache vy prosto teryaete signal bez uluchsheniya spektral'nogo kachestva. Takzhe ne imeet smysla delat' ego znachitel'no bol'she razresheniya - eto uhudshaet spektral'noe razreshenie, ne uvelichivaya signal (za isklyucheniem diffuznyh ob'ektov, no eto ne nash sluchai). Poetomu iz ispol'zuemogo razmera sheli mozhno neploho ocenit' uglovoe razreshenie instrumenta. Poschitaite, chemu sootvetstvuet 0.2".
Vse instrumenty ispol'zuyut glavnoe zerkalo, no sistema u nih priblizhena k modul'noi. Spektrometr STIS ispol'zuet na vhode kakoi-to iz fokusov opticheskoi sistemy, fizicheski on mozhet raspolagatsya nu pochti chto gde ugodno.
Sovmestim dve vashi citaty: "Habbl zhe <...> ne delaet normal'nye ul'trafioletovye snimki." i "atmosfera ne propuskaet ul'trafiolet." Nu i k chemu eto? K tomu, chto Habbl nahoditsya vne atmosfery?
"ul'trafioletovyh snimkov cherez glavnoe zerkalo Habbla vse-taki net (kakaya zhalost')." -- poprobuite vozderzhatsya ot prezhdevremennyh vyvodov i ne vydavaite zhelaemoe za deistvitel'noe.
"Poluchaetsya, chto tehnicheski 2,4-metrovoe zerkalo v kosmos mozhno i ne zapuskat', i ni odin astronom ne zametit podmeny?" -- chitaite v predydushih otvetah; ya pisal, chto podmena budet zametna.
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- Kosmicheskii teleskop "Habbl"
(scientific.ru,
19.06.1995 23:03, 4.5 KBait, otvetov: 30)
"Habbl" - eto teleskop-reflektor (vposledstvii budem upotreblyat'
ego imya bez kavychek) s zerkalom diametrom 2.4 m. - po zemnym ponyatiyam
nemalen'kii, no na zemle uzhe est' teleskopy s zerkalami diametrom do 10 m
(naprimer, Keck1 i Keck2). Im, tem ne menee daleko do Habbla.
Teleskop v osnovnom Amerikanskii, hotya krome NASA v proekte
uchastvuet Evropeiskoe Kosmicheskoe agentstvo (ESA).
O takom teleskope mechtali eshe v 40-h godah. Proektirovalsya i stroilsya on v 70-h - 80-h, i posle ryada otsrochek, byl zapushen Shattlom v aprele 1990 g. Uvy, ne vse okazalos' v poryadke, no snachala o tom, kak planirovalas' ekspluataciya Habbla. Snachala predpolagalos' spuskat' teleskop na Zemlyu s pomosh'yu Shattla cherez kazhdye 5 let, chinit', podpravlyat', sovershenstvovat', krome etogo, kazhdye 2.5 goda obsluzhivat' na orbite. Chast' "zheleza" teleskopa imela srok nadezhnosti poryadka 2.5 let. Odnako iz-za opaseniya zagryaznenii i deformacii pri pod'emah ot nazemnogo obsluzhivaniya otkazalis' i reshili oboitis' trehletnim ciklom obsluzhivaniya na orbite.
Tak vot, posle zapuska u Habbla okazalos' slegka deformirovannym glavnoe zerkalo: na 2 mikrona s krayu otnositel'no centra. 2 mikrona eto 4 - 5 dlin voln sveta, t.e. razreshenie uhudshaetsya pochti na takuyu zhe velichinu. V rezul'tate teleskop okazalsya podslepovatym i lish' umerenno prevoshodil nazemnye teleskopy v razreshenii. V 1993 godu pri polete Shattla k Habblu na teleskop byla postavlena korrektiruyushaya optika - vse ravno, chto ochki. Effekt prevzoshel vse ozhidaniya: teleskop videl luchshe, chem iznachal'no planirovalos'. Rezul'tat mozhno ocenit', vzglyanuv syuda, na snimki yadra odnoi i toi zhe galaktiki sdelannye do i posle remonta.
Sleduyushie servisnye polety Shattla byli v 1997 i 1999 godah i tozhe okazalis' ochen' uspeshnymi.
Instrumenty Kosmicheskoi observatorii:
Shirokougol'naya/planetnaya kamera (WFPC 2)
Ei sdelany pochti vse potryasayushie "peizazhnye" snimki. Sostoit iz treh bol'shih kvadratnyh matric PZS, raspolozhennyh uglom i odnoi pomen'she no s luchshim razresheniem, vstavlennoi v pustoi ugol. Iz-za takoi konstrukcii mnogie snimki imeyut vid vysherblennogo kvadrata.
Dvumernyi spektrograf (STIS)
Glavnoe preimushestvo: sposoben zapisyvat' spektr mnogih ob'ektov odnovremenno. Diapazon chuvstvitel'nosti - ot 115 nm (zhestkii ul'trafiolet) do 10000 nm (infrakrasnaya oblast') - mnogo shire, chem mozhno poluchit' na Zemle. Pole zreniya - 50 H 50 sekund dugi, matrica PZS - 1024 H 1024 pikselei.
Kamera blizhnei infrakrasnoi oblasti i mnogoob'ektnyi
spektrometr (NICMOS)Chuvstvitel'na v oblasti 0.8 - 2.5 mikrona (za predelami vidimogo diapazona). Treuet holoda, poetomu rabotaet v d'yuare (laboratornaya raznovidnost' termosa) s zamorozhennym (tverdym) azotom. Dannyi d'yuar derzhit holod godami.
Kamera dlya slabyh ob'ektov
Sdelana Evropeiskim Kosmicheskim agentstvom. Imeet rekordnoe uglovoe razreshenie: do 0.01 uglovyh sekundy. Ispol'zuet svetousilitel'nye trubki. Zvezda 21 velichiny dolzhna eksponirovat'sya so svetofil'trom, tak kak inache vse zasvetit. (Odnako, etoi kameroi sdelan unikal'nyi snimok yarchaishego ob'ekta: krasnogo sverhgiganta Betel'geize, prichem zvezda razreshena v disk s nesimmetrichnym raspredeleniem yarkosti - B.S.)
Upravlenie poletom, s'em dannyh i ih pervichnaya obrabotka osushestvlyayutsya Centrom poletov Goddarda. V techenie sutok dannye peredayutsya v Nauchnyi institut Kosmicheskogo teleskopa (Space Telescope Science Institute, STScI), STScI otvechaet za osnovnuyu obrabotku i podderzhku dannyh dlya ispol'zovaniya nauchnym soobshestvom.
Teleskop Habbl rabotaet kak mezhdunarodnaya observatoriya. Rassmatrivayutsya proekty so vsego mira, hotya konkurenciya za vremya nablyudenii ves'ma zhestkaya: prinimaetsya v srednem odin iz 10 proektov.
- Podskazhite pozhaluista po svetofil'tram Habbla
(R. G. Chertanov,
23.06.2007 13:30, 1008 Bait, otvetov: 7)
http://www.astrolab.ru/cgi-bin/manager2.cgi?id=19&num=848
"Shirokougol'naya kamera sposobna registrirovat' shirochaishii diapazon dlin voln-ot 115 nm v ul'trafioletovoi oblasti do 1100 nm v infrakrasnoi. Vnutri etoi oblasti, ispol'zuya lyuboi iz 48 vstroennyh svetofil'trov ili difrakcionnyh reshetok, mozhno vydelyat' uzkie diapazony, izmeryat' polyarizaciyu sveta ili ispol'zovat' spektrograf s nizkoi dispersiei. Pronicayushaya sila kamery - do 28'". Krome svoei osnovnoi roli shirokougol'naya kamera mozhet sluzhit' "iskatelem" dlya drugih instrumentov".
Ya by hotel uznat' parametry svetofil'trov: na kakuyu dlinu volny kazhdyi iz nih rasschitan.
I kakie iz nih real'no ispol'zuyutsya (nekotorye vrode by ne zadeistvovany).
I eshe, vdogonku, esli kto-to vstrechal, est' li gde-to v nalichii tablica prozrachnosti atmosfery dlya raznyh dlin voln na vysote 12-14 km (gde letayut samoletnye teleskopy).
- Re: Podskazhite pozhaluista po svetofil'tram Habbla
(Dmitrii Docenko,
24.06.2007 20:19, 1.5 KBait, otvetov: 6)
Citata: Ya by hotel uznat' parametry svetofil'trov: na kakuyu dlinu volny kazhdyi iz nih rasschitan.
I kakie iz nih real'no ispol'zuyutsya (nekotorye vrode by ne zadeistvovany).
I eshe, vdogonku, esli kto-to vstrechal, est' li gde-to v nalichii tablica prozrachnosti atmosfery dlya raznyh dlin voln na vysote 12-14 km (gde letayut samoletnye teleskopy).
Po fil'tram teleskopa Habbla. Ne znayu, kakie ispol'zuyutsya, no eto mozhno odnoznachno pochitat' zdes':
http://www-int.stsci.edu/instruments/wfpc2/Wfpc2_hand_current/wfpc2_cover.html
Po krivoi propuskaniya kazhdogo iz fil'trov. Kazhdoe nazvanie kodiruet "central'nuyu" dlinu volny v nm (obychno tri cifry) i klass shiriny fil'tra (N - narrow, W - wide, M - middle). Spisok i sami krivye est' v etom zhe dokumente:
http://www-int.stsci.edu/instruments/wfpc2/Wfpc2_hand_current/ch999_appendix_a_passbands.html#443899
Po propuskaniyu atmosfery. Krivuyu dlya mikrovolnovogo, infrakrasnogo i vidimogo diapazonov mozhno naiti zdes':
http://adsabs.harvard.edu/abs/1995SSRv...74...91E (nazhmite na "Full Refereed Journal Article (PDF/Postscript)")
Drugih "samoletnyh teleskopov", krome "Sofii", ya ne znayu, poetomu ogranichus' ee diapazonom.
- Re[2]: Podskazhite pozhaluista po svetofil'tram Habbla
(R. G. Chertanov,
26.06.2007 19:05, 816 Bait, otvetov: 5)
Spasibo, dannye ochen' interesnye.
Vidimyi svet imeet dliny voln ot 0,38 (fioletovyi) po 0,76 mikrometrov (krasnyi), na grafike
"Athmospheric transmission versus wavelength" eto sleva, do edinichki? Zhalko chto tam dva grafika smeshany, no zato horosho vidny kraya diapazonov.
Ya pravil'no ponimayu, chto na volnah koroche 0,3 mikrometra (3000 angstrem, 300 nm), prozrachnost' atmosfery obryvaetsya, i tam net bol'she nikakih okon? Kak zhe my zagoraem togda (ili eto sledy).
Ya vot smotryu na spisok fil'trov Habbla
http://www-int.stsci.edu/instruments/wfpc2/Wfpc2_hand_current/ch999_appendix_a_passbands3.html#440512
Tam est' fil'try s dlinoi volny koroche 3000 angstrem, no ih nemnogo v obshei masse.
Interesno delayut li s ih pomosh'yu snimki (budu iskat').
Eshe raz blagodaryu.
- Re[3]: Podskazhite pozhaluista po svetofil'tram Habbla
(Dmitrii Docenko,
26.06.2007 20:38, 1.3 KBait, otvetov: 4)
Naschet 380 nm - nu ne znayu, eto, navernoe, rekordnoe znachenie. Ya lichno vizhu ot 400-410 nm (proveryal po Bal'merovskoi serii).
Po krivoi propuskaniya atmosfery. Da, atmosfera neprozrachna nizhe primerno 320 nm; v tehnike vakuumnym ul'trafioletom schitaetsya izluchenie koroche 200 nm (t.e., svet nizhe etih dlin voln pogloshaetsya dazhe v predelah laboratorii). Dumayu, zagar voznikaet ot izlucheniya v raione 320-400 nm, no tochnyh chisel ne znayu.
Teleskop Habbla v UF diapazone ne tak uzh silen iz-za korrektiruyushego fil'tra, kotoryi postavila pervaya obsluzhivayushaya missiya. V dalekom UF (okolo 100 nm) FUSE (s ego effektivnoi ploshad'yu v 10 sm^2 !) daet spektry sravnimogo kachestva.
Nablyudeniya mozhno otsledit' na saite http://archive.stsci.edu/hst/, tam svobodno dostupny i faily dannyh, no ih obrabotka trebuet nekotoryh navykov. Dannye vysokogo urovnya (otkalibrovannye i t.d.) lezhat pod nadpis'yu "High Level Science Products". Oni v formate FITS, kotoryi umeet chitat' i pokazyvat', naprimer, programma DS9. Esli vas interesuyut sobstvenno gotovye kartinki (press-relizy i t.d.), to ih naiti slozhnee.
Derzaite!
Okon nizhe 300 nm prakticheski net. Atmosfera (uslovno) prozrachna dlya gamma-kvantov enerii 100 Gev i dal'she, no eto ochen' daleko ot optiki.
- Re[4]: Podskazhite pozhaluista po svetofil'tram Habbla
(R. G. Chertanov,
27.06.2007 22:09, 710 Bait, otvetov: 3)
(DmitriiDocenko)
>Teleskop Habbla v UF diapazone ne tak uzh silen iz-za korrektiruyushego fil'tra, kotoryi postavila pervaya obsluzhivayushaya missiya.
Znaya harakter amerikancev, mne kazhetsya, proshe bylo by sdelat' kachestvennye snimki s samoleta (v chastnosti, zerkalo u Sofii takoe zhe po diametru, kak i u Habbla), i vydat' ih za Habblovskie.
Kak Vy dumaete, eto tehnicheski vozmozhno, ili zhe specialisty-astrofiziki po kakim-to opredelennym priznakam srazu zhe uvidyat podmenu? Est' li voobshe takie priznaki, ili tam raznicu dazhe specialistu prosto tak ne otlichit'?
- Re[5]: Podskazhite pozhaluista po svetofil'tram Habbla
(Dmitrii Docenko,
28.06.2007 12:12, 1.6 KBait, otvetov: 2)
Citata: Znaya harakter amerikancev, mne kazhetsya, proshe bylo by sdelat' kachestvennye snimki s samoleta (v chastnosti, zerkalo u Sofii takoe zhe po diametru, kak i u Habbla), i vydat' ih za Habblovskie.
Kak Vy dumaete, eto tehnicheski vozmozhno, ili zhe specialisty-astrofiziki po kakim-to opredelennym priznakam srazu zhe uvidyat podmenu? Est' li voobshe takie priznaki, ili tam raznicu dazhe specialistu prosto tak ne otlichit'?
Oi, nu chto vy. I, glavnoe, kak i zachem?
Vse nablyudeniya teleskopa Habbla stanovyatsya dostupny vsem cherez god, vklyuchaya nablyudeniya po kalibrovke. To est' nablyudenie, kotoroe "bylo", no pod kotoroe ne bylo otdano vremya, srazu budet zametno.
Dalee, Habbl byl unikalen svoim vysokim uglovym razresheniem. Ni odnim drugim teleskopom takogo ne povtorit' (v poslednie gody adaptivnaya optika pozvolyaet sdelat' chto-to podobnoe, no na uzkom pole zreniya). Samoletnym uzh tochno.
Krome togo, u Habbla svoya, sovershenno osobennaya, PSF (point spread function), kotoraya sil'no otlichaetsya ot drugih teleskopov. Svoi shum detektorov. Svoi razmer pikselei. Svoi vklad ot kosmicheskih luchei. I tak dalee. Chtoby poddelat' nablyudeniya Habbla, nuzhno ih proizvesti na teleskope luchshe Habbla, a zatem uhudshit' parametry tak, chtoby "mimikrirovat'". A takoe poka nevozmozhno :)
- Re[6]: Podskazhite pozhaluista po svetofil'tram Habbla
(R. G. Chertanov,
28.06.2007 14:46, 1.4 KBait, otvetov: 1)
>Dalee,
Habbl byl unikalen svoim vysokim uglovym razresheniem. Ni odnim drugim
teleskopom takogo ne povtorit' (v poslednie gody adaptivnaya optika
pozvolyaet sdelat' chto-to podobnoe, no na uzkom pole zreniya). Samoletnym
uzh tochno.
Est' samoletnyi teleskop SOFIA s zerkalom 2.5 metrov. Zerkalo Habbla - 2.4 metra.
Vy schitaete chto u samoletnogo 2,5-metrovogo zerkala zametno huzhe uglovoe razreshenie?
A ved' na samolet vodruzit' takoe bol'shoe zerkalo navernoe gorazdo proshe chem na sputnik (inache by vmesto Sofii zapustili eshe odin Habbl). I obsluzhivat' ego legche.
>Krome togo, u Habbla svoya, sovershenno osobennaya, PSF (point spread function), kotoraya sil'no otlichaetsya ot drugih teleskopov. Svoi shum detektorov. Svoi razmer pikselei. Svoi vklad ot kosmicheskih luchei. I tak dalee. Chtoby poddelat' nablyudeniya Habbla, nuzhno ih proizvesti na teleskope luchshe Habbla, a zatem uhudshit' parametry tak, chtoby "mimikrirovat'". A takoe poka nevozmozhno :)
Eto vse ponyatno, no samoletnyi teleskop tozhe mozhet imet' svoi shum detektorov i razmer pikselei.
A tot parametr, na kotoryi ya hotel posmotret' (ul'trafioletovye luchi) - okazalsya uhudshennym (kak budto v kosmose nahoditsya malen'koe zerkalo, a horoshie (no ne ul'trafioletovye) snimki delayut vse eti gody samoletom a lya SOFIA)...
- Re[7]: Podskazhite pozhaluista po svetofil'tram Habbla
(Dmitrii Docenko,
28.06.2007 15:58, 2.0 KBait)
U drugogo teleskopa budut drugie parametry i pri obrabotke dannyh storonnimi astroromami-nablyudatelyami eto im budet ochevidno.Citata: Eto vse ponyatno, no samoletnyi teleskop tozhe mozhet imet' svoi shum detektorov i razmer pikselei.
A tot parametr, na kotoryi ya hotel posmotret' (ul'trafioletovye luchi) - okazalsya uhudshennym (kak budto v kosmose nahoditsya malen'koe zerkalo, a horoshie (no ne ul'trafioletovye) snimki delayut vse eti gody samoletom a lya SOFIA)...
0.2 uglovyh sekundy - eto ne shutka. Esli razmer zerkala 2.5 metra, to za vremya nablyudeniya ono dolzhno drozhat' ne bolee, chem na 2.5 mikrona otnositel'no vtorichnogo zerkala i drugih chastei teleskopa (a v samolete vibracii ochen' mnogo). Bolee togo, napravlenie samoleta dolzhno podderzhivat'sya postoyannym s takoi zhe tochnost'yu, to est' ne dolzhno byt' nikakih (dazhe ochen' malen'kih) vozdushnyh yam. Opyat'-taki, v vozduhe budet razmytie izobrazheniya prosto iz-za ego peremennyh neodnorodnostei. Krome togo, atmosfera vse ravno neprozrachna v dalekom UF, gde u Habbla est' mnozhestvo nablyudenii (ya znayu o spektroskopii, no, navernoe, est' i kartinki).
Dlya SOFIA vse problemy v 10 i bolee raz menee aktual'ny iz-za hudshego uglovogo razresheniya v IK diapazone.
Krome togo, v kosmos vyvesti chto by to ni bylo nezamechennym nevozmozhno. Katalogiziruetsya vse bol'she 20 sm (kazhetsya).
Esli by byl samolet tipa SOFIA dlya nablyudeniya UF izlucheniya, to eto tozhe ne ostalos' by nezamechennym astronomami, tak kak on byl by unikal'nym instrumentom i pri ego sozdanii nuzhno bylo by preodolet' kuchu specificheskih tehnicheskih problem.
Net, ne veryu
- Re: Kosmicheskii teleskop "Habbl"
(R. G. Chertanov,
28.06.2007 21:15, 1.3 KBait, otvetov: 2)
Samoletnye teleskopy primenyayutsya uzhe bolee 30 let, i tam vibraciyu kak-to udaetsya gasit'.
http://www.forextimes.ru/news/hnews63550p.htm
"Chtoby vibraciya samoleta ne peredavalas' teleskopu, ego budet uderzhivat' v neizmennom polozhenii sistema giroskopov i gidravlicheskih podvesok".
U menya est' podozrenie, chto vibraciyu udaetsya gasit' polnost'yu...
Kstati, vot eshe sposob, kak delat' kachestvennye snimki na 2,5-metrovom zerkale:
http://lenta.ru/news/2005/06/13/nasa/
NASA zapustilo v voskresen'e co shvedskogo poligona Esrange teleskop BLAST na vozdushnom share. ...
BLAST snabzhen dvuhmetrovym zerkalom, to est' nenamnogo ustupaet 2,5-metrovomu kosmicheskomu teleskopu Hubble v kolichestve ulavlivaemogo sveta. ... Gigantskii aerostat - diametrom 120 i dlinoi 140 metrov - dostavit BLAST na vysotu 40 kilometrov.
Sprashivaetsya, zachem vse eti slozhnosti s sharami i samoletami, esli uzhe otrabotana tehnologiya zapuska kosmicheskih Habblov? Ved' povtoryat' (kak rossiiskie Protony i Soyuzy) v desyatki raz deshevle.
- Re[2]: Kosmicheskii teleskop "Habbl"
(Dmitrii Docenko,
29.06.2007 11:05, 1.8 KBait)
"Chtoby vibraciya samoleta ne peredavalas' teleskopu, ego budet uderzhivat' v neizmennom polozhenii sistema giroskopov i gidravlicheskih podvesok".
Da, no v tehnike inogda ochen' vazhen i faktor dvoiki. A dlya UF snimkov (dlina volny na poryadok koroche), sootvetstvenno, i podderzhanie napravleniya teleskopa trebuetsya na poryadok tochnee. Vprochem, ya konkretnyh cifr ne znayu; esli vy znaete, napishite.
"U menya est' podozrenie, chto vibraciyu udaetsya gasit' polnost'yu..."
Polnost'yu nikogda nichego ne byvaet Mozhno oslabit' na n dB. Naskol'ko
veliko eto n, ya ne v kurse. A vy?
"Sprashivaetsya, zachem vse eti slozhnosti s sharami i samoletami, esli uzhe otrabotana tehnologiya zapuska kosmicheskih Habblov? Ved' povtoryat' (kak rossiiskie Protony i Soyuzy) v desyatki raz deshevle."
Vy znaete konkretnye cifry -- stoimost' zapuska Habbla; stoimost' ego podderzhki i t.d.? Tol'ko postroika (bez zapuska) oboshlas' bolee chem v milliard dolarov. Vot citaty:
"From its original total cost estimate of about 400 million dollars, the telescope had by now cost over US$2.5 billion to construct. Hubble's cumulative costs up to this day are estimated to be several times higher still, with U.S. ... estimated at between 4.5 and 6 billion USD and Europe's financial contribution at 593 million Euros (1999 estimate)"
"The shuttle mission to refurbish the Hubble Space Telescope one last time in May 2008 will cost about $900 million."
Zamet'te: nachal'naya stoimost' (postroit' + zapustit') uzhe men'she poloviny polnyh zatrat (v osnovnom, dumayu, iz-za treh obsluzhivayushih missii). Tak chto dazhe esli vy umen'shite do nulya stoimost' zapuska, sil'no polnye zatraty eto ne umen'shit.
- Re[2]: Kosmicheskii teleskop "Habbl"
(pointedlynovell liu,
24.11.2022 5:53, 7.8 KBait)
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- Re: Kosmicheskii teleskop "Habbl"
(R. G. Chertanov,
29.06.2007 14:54, 3.2 KBait, otvetov: 13)
(DmitriiDocenko)
1) Vy uvereny, chto snimki v ul'trafioletovom diapazone budut beznadezhno isporcheny (a ne prosto priobretut to zhe uglovoe razreshenie, chto i infrakrasnye), pri prochih ravnyh usloviyah (kachestvo i razmer zerkala, vibraciya, tochnost' pozicionirovaniya i gidirovaniya)? Ul'trafiolet v dannom sluchae ved' nichego ne uhudshaet. Poluchitsya snimok, shodnyi po kachestvu s infrakrasnym ili vidimym izlucheniem: sam po sebe ul'trafiolet ne yavlyaetsya uhudshayushim snimok faktorom. To est', na podobnyi Sofii samolet (ili podobnyi Blastu vozdushnyi shar) vpolne mogli by ustanovit' i ul'trafioletovyi priemnik, i priemnik vidimogo diapazona. I my by togda sravnili, chto pokazyvaet Habbl, i chto pokazyvayut eti ustroistva. Kstati, ya vstrechal infu pro 4-metrovyi samoletnyi teleskop EKA - nichego pro nego ne slyshno?
2) Poisk nahodit svedeniya imenno pro polnoe gashenie vibracii (kotoroi, okazyvaetsya, i na sputnike hvataet).
http://www.novosti-kosmonavtiki.ru/content/numbers/211/14.shtml
Apparatura VISS yavlyaetsya eksperimental'noi polnost'yu zamknutoi precizionnoi sistemoi, rabota kotoroi ne zavisit ot drugih ustroistv. Ona prednaznachena dlya obespecheniya uslovii raboty chuvstvitel'nyh opticheskih priborov putem polnogo gasheniya vibracionnyh vozmushenii. VISS predstavlyaet soboi platformu, smontirovannuyu na bazovom bloke KA na shesti dempferah, razmeshennyh v vershinah pravil'nogo shestiugol'nika (t.n. platforma Styuarta). Takaya konstrukciya pozvolyaet obespechit':
polnuyu izolyaciyu (po vsem shesti stepenyam svobody) platformy s chuvstvitel'noi apparaturoi ot vibracionnyh vozmushenii, sozdavaemyh kosmicheskim apparatom;
podavlenie vibracii, vyzyvaemoi rabotoi otdel'nyh elementov chuvstvitel'noi apparatury (naprimer, kriogennym ohladitelem IKpriemnikov);
plavnoe upravlenie razvorotom vokrug lyuboi iz treh osei vrasheniya.
Planiruetsya, chto v hode eksperimenta VISS obespechit izolyaciyu i gashenie vibracionnyh vozmushenii s urovnem bolee
20 dB, a takzhe plavnost' razvorota 0.3 s chastotoi 2 Gc.
Mne ponravilas' stat'ya pro gashenie vibracii:
http://physics.nad.ru/Physics/Cyrillic/spri_txt.htm
3) Pri kopirovanii izdelii rezko snizhaetsya ih sebestoimost' Privedu primer Apollona - 7 mlrd za pervyi obrazec i 0,4 mlrd - za posleduyushie.
http://moon.thelook.ru/book/15.htm
Soglasno dannym NASA, zatraty na programmu "Apollon" sostavili 20-25 milliardov dollarov [21,25]. Izvestno, chto pri razrabotke novyh tehnologii ili izdelii pervye obrazcy stoyat dorogo, no stoimost' proizvodstva posleduyushih obrazcov nachinaet rezko snizhat'sya. Voz'mem tu zhe samuyu raketu Saturn-5. Ee razrabotka, a, znachit, i pervyi ekzemplyar stoili okolo 7 mlrd. $. No uzhe posleduyushie ekzemplyary stoili po 0,4 mlrd. za shtuku [22]. Povtoryat' vsegda deshevle.
- Re[2]: Kosmicheskii teleskop "Habbl"
(Dmitrii Docenko,
2.07.2007 10:22, 943 Bait, otvetov: 12)
"Vy uvereny, chto snimki v ul'trafioletovom diapazone budut beznadezhno isporcheny (a ne prosto priobretut to
zhe uglovoe razreshenie, chto i infrakrasnye), pri prochih ravnyh usloviyah"
Ne zabyvaite pro difrakciyu. Uglovoe razreshenie "Habbla" v UF v 5-10 raz luchshe, chem v IK.
"Kstati, ya vstrechal infu pro 4-metrovyi samoletnyi teleskop EKA - nichego pro nego ne slyshno?"
Ya ne slyshal.
"Planiruetsya, chto v hode eksperimenta VISS obespechit izolyaciyu i gashenie vibracionnyh vozmushenii s urovnem bolee 20 dB, a takzhe plavnost' razvorota 0.3 s chastotoi 2 Gc. "
Vot-vot. 20 dB = 100 raz. Ya ne znayu, kakomu drozhaniyu teleskopa eto sootvetstvuet pri (neizvestnom mne) spektre vibracii samoleta.
"Pri kopirovanii izdelii rezko snizhaetsya ih sebestoimost'"
Da. - Re[3]: Kosmicheskii teleskop "Habbl"
(R. G. Chertanov,
3.07.2007 15:54, 1.4 KBait, otvetov: 11)
>Ne zabyvaite pro difrakciyu. Uglovoe razreshenie "Habbla" v UF v 5-10 raz luchshe,
chem v IK.
Esli nalozhit' vibraciyu na vidimyi svet i na IK, konechnyi rezul'tat-to v bolee korotkovolnovom uchastke budet ne huzhe, chem u IK, ne tak li. A dazhe luchshe, esli vibraciyu udaetsya effektivno gasit'. A sudya po nalichiyu v vozduhe Sofii, gasit' ee dlya zerkala diametrom 2,4 metra udaetsya vpolne effektivno.
To est', u nas est' uhudshayushii faktor A, i on nakladyvaetsya na pomehi B i b.
A - eto vibraciya, B i b - eto uhudshenie, vnosimoe dlinoi volny (v sluchae infrakrasnyh luchei - bol'shoe, v sluchae vidimyh luchei - pomen'she).
Snimki sdelannye s pomehami A i B (infrakrasnye) budut nu nikak ne luchshe, chem A i b (vidimye).
Poetomu NASA dolzhno ob'yasnit', pochemu u nih vidimye i ul'trafioletovye snimki ne takie horoshie po kachestvu, kak eto pozvolyaet zerkalo. I ono ob'yasnilo - tipa polomka vot tut u nas, doblestnye astronavty (v svoih perchatkah) chinili-chinili, no ul'trafiolet pri etom prishlos' isportit' okonchatel'no.
Vopros zapustit' vtoroi Habbl dazhe ne stavilsya. Poetomu i voznikayut somneniya, a ne s samoleta ili s shara li oni delayut svoi zamechatel'nye ne-ul'trafioletovye snimki...
- Re[4]: Kosmicheskii teleskop "Habbl"
(Dmitrii Docenko,
14.07.2007 17:28, 2.0 KBait, otvetov: 10)
Uvazhaemyi R.G.!
U menya takoe vpechatlenie, chto vy ili ne chitaete, ili ne vosprinimaete moi otvety.
a. Naschet vibracii i difrakcii. Razreshenie, opredelyaemoe vibraciei, ne zavisit ot dliny volny (vy sami pishete "ne huzhe, chem u IK"). Razreshenie, opredelyaemoe difrakciei, proporcional'no dline volny (ya uzhe pisal, "Uglovoe razreshenie "Habbla" v UF v 5-10 raz luchshe, chem v IK.").
V etom i delo. Esli vy optimiziruete teleskop pod IK, v UF razreshenie budet ne huzhe, no vryad li budet mnogo luchshe.
K tomu zhe atmosfera sovershenno neprozrachna okolo 100-150 nm, gde u Habbla est' kak minimum spektry (naprimer, http://adsabs.harvard.edu/cgi-bin/bib_query?2004ApJS..152...29P; eto nichem ne osobennaya stat'ya, prosto ya s nei rabotal). Eti spektry polucheny s shirinoi sheli 0."2, dlya zemnyh (i letayushih) teleskopov eto bessmyslenno, tak kak razreshenie teleskopa mnogo huzhe (men'she 0."5, naskol'ko ya znayu, nigde ne primenyaetsya). Esli vy nu sovsem ne verite, ya dayu ssylku na arhiv ishodnyh dannyh; posmotrite, prover'te: http://archive.stsci.edu/mastbibref.php?bibcode=2004ApJS..152...29P
Dalee. "A sudya po nalichiyu v vozduhe Sofii, gasit' ee dlya zerkala diametrom 2,4 metra udaetsya vpolne effektivno." Otvet'te, esli ne slozhno, mne na vopros: kakoe razreshenie SOFII na 300 nm? Ili na drugih dlinah voln v UF. Vse eti obshie slova vrode "vpolne effektivno" ochen' krasivy, no nichego ne dokazyvayut. Chisla dokazhut vse.
b. "Poetomu NASA dolzhno ob'yasnit', pochemu u nih vidimye i ul'trafioletovye snimki ne takie horoshie po kachestvu, kak eto pozvolyaet zerkalo."
Opustim vopros o tom, chto vam dolzhno NASA.
Snova, pohozhe, vy ne chitali moi otvety. Razreshenie u UF snimkov/spektrov otlichnoe. Effektivnost' malen'kaya. Ya pisal "Teleskop Habbla v UF diapazone ne tak uzh silen iz-za korrektiruyushego fil'tra", no ne poyasnil, chto eto otnositsya k chuvstvitel'nosti, a ne k razresheniyu.
Ya razveyal vashi somneniya? - Re[5]: Kosmicheskii teleskop "Habbl"
(R. G. Chertanov,
8.08.2007 3:15, 1.9 KBait, otvetov: 9)
Uvazhaemyi Dmitrii!
U menya ostalos' sleduyushee somnenie.
Ya ostavlyu obsuzhdenie pro vibraciyu, t.k. est' vozdushnyi shar BLAST s teleskopom primerno habblovskogo diametra. Nikakoi vibracii tam konechno net, i s nego mozhno delat' snimki, analogichnye po kachestvu snimkam Habbla (kstati Vy ne videli etih snimkov?). Za odnim isklyucheniem - atmosfera ne propuskaet ul'trafiolet.
Habbl zhe (kakoe sovpadenie) tozhe ne delaet normal'nye ul'trafioletovye snimki.
A vopros u menya naschet spektrov: deistvitel'no li dlya ih polucheniya neobhodimo zerkalo bol'shogo (240 sm) diametra, ili zhe mozhet byt' dostatochno i zerkala pomen'she (a mozhet byt' voobshe snimki spektra delayutsya nezavisimo ot glavnogo zerkala?).
Naprimer, ya poshel po rekomendovannoi Vami ssylke
http://archive.stsci.edu/mastbibref.php?bibcode=2004ApJS..152...29P
vybral pervyi popavshiisya spektr
http://archive.stsci.edu/cgi-bin/mastpreview?mission=hst&dataid=O4EC10010
Iz etoi ssylki sleduet, chto dlya polucheniya etogo grafika ispol'zuetsya instrument STIS. A kak etot STIS vyglyadit - eto sluchaino ne korobochka sverhu korpusa, kotoroi vovse ne nuzhno glavnoe zerkalo?
http://en.wikipedia.org/wiki/High_Resolution_Spectrograph
Eto byl predshestvennik STISa. Vot bolee tochnaya ssylka
http://www.spacetelescope.org/about/general/instruments/stis.html
Tam k sozhaleniyu neponyatno kak vyglyadit ustroistvo. Ego gabarity 2.2h0.9h0.9 m, 318 kg dostatochno skromnye.
To est', ul'trafioletovyh snimkov cherez glavnoe zerkalo Habbla vse-taki net (kakaya zhalost').
Poluchaetsya, chto tehnicheski 2,4-metrovoe zerkalo v kosmos mozhno i ne zapuskat', i ni odin astronom ne zametit podmeny?
Ili est' priznak, po kotoromu mozhno tochno skazat', chto takoe bol'shoe i po-svoemu unikal'noe zerkalo est' imenno na sputnike (a ne na samolete ili share)?
- >> Re[6]: Kosmicheskii teleskop "Habbl"
(Dmitrii Docenko,
8.08.2007 12:57, 2.3 KBait, otvetov: 8)
Hm. Nu, ya dumal, vy znaete, kak poluchayutsya spektry. Seichas ob'yasnyu.
Ob'ektiv teleskopa formiruet izobrazhenie uchastka neba na fokal'noi ploskosti. V prosteishem sluchae tam mozhet stoyat' fotoplastinka ili PZS-matrica, ili zhe eto izobrazhenie astronom mozhet razglyadyvat' cherez lupu, kotoraya v dannom sluchae nazyvaetsya okulyarom. Uglovoe razreshenie v ideal'nom sluchae opredelyaetsya difrakciei.
Vmesto etogo fokal'nuyu ploskost' mozhno zakryt' neprozrachnoi plastinoi, ostaviv v nei tol'ko nebol'shuyu dyrku (obychno ispol'zuetsya shel', no ee mozhno predstavit', kak summu nakih dyrok). Za etoi dyrkoi stavyat dispergiruyushii element (prizmy, difrakcionnyyu reshetky, eshelett), posle kotorogo svet razdelyaetsya na spektr. Opticheskaya sistema snova sobiraet etot svet na sleduyushei fokal'noi ploskosti. Takim obrazom, iz tochki poluchetsya 1-mernyi spektr. Iz sheli, sootvetstvenno, poluchaetsya 2-mernyi spektr (napravlenie dispersii dolzhno byt' perpendikulyarno sheli).
Razmer sheli (v uglovyh edinicah) ne imeet smysla delat' men'she, chem razreshenie teleskopa - inache vy prosto teryaete signal bez uluchsheniya spektral'nogo kachestva. Takzhe ne imeet smysla delat' ego znachitel'no bol'she razresheniya - eto uhudshaet spektral'noe razreshenie, ne uvelichivaya signal (za isklyucheniem diffuznyh ob'ektov, no eto ne nash sluchai). Poetomu iz ispol'zuemogo razmera sheli mozhno neploho ocenit' uglovoe razreshenie instrumenta. Poschitaite, chemu sootvetstvuet 0.2".
Vse instrumenty ispol'zuyut glavnoe zerkalo, no sistema u nih priblizhena k modul'noi. Spektrometr STIS ispol'zuet na vhode kakoi-to iz fokusov opticheskoi sistemy, fizicheski on mozhet raspolagatsya nu pochti chto gde ugodno.
Sovmestim dve vashi citaty: "Habbl zhe <...> ne delaet normal'nye ul'trafioletovye snimki." i "atmosfera ne propuskaet ul'trafiolet." Nu i k chemu eto? K tomu, chto Habbl nahoditsya vne atmosfery?
"ul'trafioletovyh snimkov cherez glavnoe zerkalo Habbla vse-taki net (kakaya zhalost')." -- poprobuite vozderzhatsya ot prezhdevremennyh vyvodov i ne vydavaite zhelaemoe za deistvitel'noe.
"Poluchaetsya, chto tehnicheski 2,4-metrovoe zerkalo v kosmos mozhno i ne zapuskat', i ni odin astronom ne zametit podmeny?" -- chitaite v predydushih otvetah; ya pisal, chto podmena budet zametna. - Re[7]: Kosmicheskii teleskop "Habbl"
(R. G. Chertanov,
8.08.2007 18:17, 890 Bait, otvetov: 7)
>Iz sheli, sootvetstvenno,
poluchaetsya 2-mernyi spektr
Znachit li eto, chto znachitel'naya chast' ploshadi zerkala prosto ne ispol'zuetsya, t.k. zakryta shel'yu?
>Vse instrumenty ispol'zuyut glavnoe zerkalo
Pochemu zhe togda imenno dlya spektrometra ne proyavlyaetsya ta nepoladka, kotoraya yakoby meshaet Habblu delat' kachestvennye UF-snimki? Da i v pervyh postah Vy zhe pisali:
<i>"Teleskop Habbla v UF diapazone ne tak uzh silen iz-za korrektiruyushego fil'tra, kotoryi postavila pervaya obsluzhivayushaya missiya. V dalekom UF (okolo 100 nm) FUSE (s ego effektivnoi ploshad'yu v 10 sm^2 !) daet spektry sravnimogo kachestva"</i>.
To est', dlya polucheniya spektrov sravnimogo kachestva mozhno bylo by vzyat' zerkalo pomen'she i polegche, ne pravda li.
- Re[8]: Kosmicheskii teleskop "Habbl"
(M. Yu. Yakimov,
8.08.2007 21:01, 514 Bait, otvetov: 5)
Habbl delaet snimki v ul'trafiolete i pokazal svoyu effektivnost' i v etoi oblasti. Tem ne menee, Vy pravy, kogda govorite, chto na special'no sproektirovannom pod UF teleskope mozhno dostich' gorazdo luchshih rezul'tatov, chem na Habble (V UF-diapazone), i pri etom bolee prostymi sredstvami. Etu ideyu razvivaet gruppa sotrudnikov v INASAN i proekt blizok k zaversheniyu. Poznakomit'sya s nim mozhno na saite http://www.inasan.rssi.ru/rus/WSO/index.html
- Re[9]: Kosmicheskii teleskop "Habbl"
(R. G. Chertanov,
11.08.2007 5:37, 1.9 KBait, otvetov: 4)
(M. Yu. Yakimov)
Nu otlichno, ya rad za razrabotchikov INASAN. A kak Vy dumaete, pochemu SShA ne osilili v horoshem kachestve (bol'shIm zerkalom) imenno ul'trafioletovyi diapazon (na kakom-to drugom sputnike, naprimer). Ved' u nih bol'she resursov vsyakogo roda (deneg naprimer), a samyi interesnyi diapazon (kotoryi nel'zya poluchit' ni s zemli, ni s vozdushnogo shara) oni kak-to propustili. Neuzheli oni dal'she vozdushnogo shara 240-sm zerkalo i ne zapuskali?
(Dmitrii Docenko)
>""Nepoladka", tochnee, prisutstvie korrektiruyushego fil'tra, proyavlyaetsya v umen'shenii effektivnoi ploshadi, a ne uhudshenii uglovogo razresheniya".
Vy tol'ko chto skazali vazhnuyu vesh'. Davaite predstavim, chto u nas est' zerkalo teleskopa 240 sm. A teper' v zerkalo (vot nezadacha) popal meteorit, i otkololis' kraya zerkala (ono stalo ne 240 sm, a skazhem 40 sm diametrom). Chto u zerkala pri etom umen'shilos'? U zerkala pri etom umen'shilas' effektivnaya ploshad' (ploshad' kazhdogo kusochka deistvitel'no men'she, chem vsego zerkala). Pri etom sohranilos' (ostalos' prezhnim) uglovoe razreshenie (t.k. krivizna zerkala ne izmenilas').
To est', "nepoladka" poluchaetsya takogo roda, chto na orbite my imeem ekvivalent malen'kogo zerkala.
A ved' malen'koe zerkalo gorazdo proshe zapustit' na orbitu, chem bol'shoe, ne pravda li? A ostal'nye diapazony fotkat' s vozdushnogo shara (ili samoleta) bol'shim zerkalom...
Interesno, kakie mogut byt' dokazatel'stva, chto Habbl eto Habbl, a ne kombinaciya iz "malen'kogo" sputnika i "bol'shogo" vozdushnogo shara (ili samoleta)? Po hronometrazhu mozhet byt' chto-nibud'?
- Re[10]: Kosmicheskii teleskop "Habbl"
(Dmitrii Docenko,
11.08.2007 23:08, 1.2 KBait, otvetov: 3)
> zerkalo <...> stalo ne 240 sm, a skazhem 40 sm diametrom. <...> U zerkala pri etom umen'shilas' effektivnaya ploshad'. Pri etom sohranilos' <...> uglovoe
razreshenie (t.k. krivizna zerkala ne izmenilas').
Ya uzhe pisal vyshe. Ne vydavaite zhelaemoe za deistvitel'noe.
Kak sleduet iz, po-vidimomu, neizvestnoi vam teorii difrakcii, uglovoe razreshenie menyaetsya, poskol'ku izobrazhenie, proizvodimoe ideal'noi linzoi v fokal'noi ploskosti, yavlyaetsya Fur'e-preobrazovaniem vhodnogo otverstiya (v dannom sluchae, formy zerkala). Uglovoe razreshenie ne zavisit ot fokusnogo rasstoyaniya.
> Interesno, kakie mogut byt' dokazatel'stva, chto Habbl eto Habbl, a ne kombinaciya iz "malen'kogo" sputnika i "bol'shogo" vozdushnogo shara (ili samoleta)?
Ya uzhe pisal, poetomu vynuzhden povtorit'sya. Vysokoe uglovoe razreshenie; PSF v UF i vidimyh diapazonah; kolichestvo kosmicheskih luchei na matrice; shum, razmery, chuvstvitel'nost', vzaimnoe polozhenie detektorov; razmer pikselei, ...
Vy pisali, chto eto vam "vse ponyatno", no iz nashei diskussii u menya v etom postepenno zakradyvaetsya somnenie. Nadeyus', vy ponimaete, chto PSF - ochen' ser'eznyi argument. - Re[11]: Kosmicheskii teleskop "Habbl" (R. G. Chertanov, 12.08.2007 5:22, 2.1 KBait, otvetov: 2) Soglashus', Vy pravy, pri malen'kom zerkale umen'shaetsya uglovoe razreshenie (ya sputal s drugoi harakteristikoi). No naprimer na etom snimke Yupitera v vidimyh i UF-luchah rezko razlichaetsya kachestvo. http://hubblesite.org/newscenter/archive/releases/1994/31/image/a/format/web_print/ A tochno li u etih snimkov odinakovoe, kak Vy pishete, uglovoe razreshenie? >""Nepoladka", tochnee, prisutstvie korrektiruyushego fil'tra, proyavlyaetsya v umen'shenii effektivnoi ploshadi, a ne uhudshenii uglovogo razresheniya". Mozhet tam i effektivnaya ploshad', i uglovoe razreshenie imenno dlya UF-diapazona sootvetstvuyut zerkalu men'shemu, chem zayavleno? Inache by ne bylo takoi zhutkoi zernistosti na vtorom snimke, ne tak li. Da i kstati ne dolzhen li ul'trafiolet uluchshit' eto samoe uglovoe razreshenie (chem koroche dlina volny, tem ved' luchshe razreshenie). A na snimkah my vidim naoborot rezkoe uhudshenie pri yakoby tom zhe zerkale. Soglasites', chto zdes' yavno chto-to ne tak. Versiya pro ustanovlennyi astronavtami korrektiruyushii fil'tr, kotoryi im tam vse uhudshil, konechno, interesnaya, no ona trebuet bolee podrobnyh svedenii, a ih-to kak raz i net. Chto soboi predstavlyaet eta shtuka, pochemu ona uhudshila imenno UF-diapazon - my ved' ne znaem. Ili u Vas est' polnaya yasnost' na etot schet? Kstati predstav'te proceduru ustanovki korrektiruyushego fil'tra - eto zhe sverhtochnyi pribor, a u kosmonavta perchatki edva gnutsya. Oni ne sumeli sdelat' shtatno, pol'zuyas' vsemi priborami, na Zemle, no yakoby u nih vse poluchilos' v kosmose. Da i esli neudacha postigla s odnim habblom, pochemu ne zapustili vtoroi, ispravnyi (ved' rashody na NIOKR, kotorye s'edayut l'vinuyu dolyu sredstv, uzhe byli poneseny). Ne inache kak zdes' chto-to ne tak: odna otmazka NASA gromozditsya na druguyu, i v itoge my imeem te zhe snimki, kotorye sdelal by i vozdushnyi shar BLAST... Naschet vozmozhnosti poddelki PSF - na fone takogo uhudsheniya snimka lyubaya komp'yuternaya obrabotka vneset, mne kazhetsya, ne slishkom zametnye iskazheniya. Da i pikselyam yarkost' podkorrektirovat' po snyatym eshe na zemle harakteristikam - po-moemu eto neslozhno.
- Re[12]: Kosmicheskii teleskop "Habbl"
(Dmitrii Docenko,
12.08.2007 16:44, 2.2 KBait, otvetov: 1)
Mne prosto nadoelo vas ubezhdat' Otvechu na vashi voprosy.
> A tochno li u etih snimkov odinakovoe <...> uglovoe razreshenie? <...> uglovoe razreshenie imenno dlya UF-diapazona sootvetstvuyut zerkalu men'shemu, chem zayavleno. Inache by ne bylo takoi zhutkoi zernistosti na vtorom snimke, ne tak li.
Nu, v kommentariyah k etomu snimku napisano "The grainy appearance of Jupiter in the FUV is due to the darkness of the planet at this wavelength." Ya tak i dumal, no ved' vas eto ne ubedit, da? Razreshenie v etom sluchae nuzhno smotret' po yarchaishim uchastkam snimka, v dannom sluchae eto polyarnoe siyanie. Ya by skazal, chto razreshenie
UF ne huzhe, chem vidimogo snimka.
> Chto soboi predstavlyaet eta shtuka, pochemu ona uhudshila imenno UF-diapazon - my ved' ne znaem. Ili u Vas est' polnaya yasnost' na etot schet?
Ideya v tom, chto material fil'tra pochti ne propuskaet dalekii UF. Koefficient propuskaniya tam ne vyshe 10%. Poetomu effektivnost' padaet na poryadok, a difrakcionnoe razmytie izobrazheniya ne menyaetsya. Pochemu imenno UF - eto yasno iz obshei teorii vzaimodeistviya sveta s dielektrikami (UF nahoditsya v hvoste polosy poglosheniya).
> Oni ne sumeli sdelat' shtatno, pol'zuyas' vsemi priborami, na Zemle, no yakoby u nih vse poluchilos' v kosmose.
Neobhodimost' ustanovki fil'tra stala yasna posle zapuska teleskopa, poskol'ku pri zapuske byla sdvinuta opticheskaya sistema (ne znayu tochno, mozhet, osnovnoe zerkalo pognulos' ili chto-nibud' eshe).
> Da i esli neudacha postigla s odnim habblom, pochemu ne zapustili vtoroi, ispravnyi
Ne znayu. Zaderzhka sostavila by kak minimum 2-3 goda, no eto ne tak mnogo. Mozhet, eto kak raz byl politicheskii vopros. No, chestno govorya, ne znayu.
> Naschet vozmozhnosti poddelki PSF - na fone takogo uhudsheniya snimka lyubaya komp'yuternaya obrabotka vneset, mne kazhetsya, ne slishkom zametnye iskazheniya.
Eto naivno. Pozvolyu sebe predpolozhit', chto vy ne rabotali s Habblovskimi dannymi.
- Re[13]: Kosmicheskii teleskop "Habbl"
(R. G. Chertanov,
13.08.2007 14:11, 4.0 KBait)
>v dannom sluchae eto polyarnoe siyanie
Izvestno, chto snimki s Habbla podvergayutsya podmeshivaniyu sluchainogo shuma i komp'yuternoi obrabotke - poetomu tam koe-chto i mozhet vyglyadet' s bolee vysokim razresheniem, chem est' na samom dele.
http://naturalist.rarib.ru/habbl.htm
"Primenyaya sochetanie raznoi tehniki obrabotki izobrazhenii (podmeshivanie psevdosluchainogo shuma, vydelenie podvyborki, obratnogo preobrazovaniya) (dithering, subsampling and deconvolution), astronomy sozdali odno iz naibolee chetkih izobrazhenii udalennogo ob'ekta, kotoroe kogda-libo delalos' kosmicheskim teleskopomHabbla. Na poluchennoi kartinke vidny udivitel'nye podrobnosti"
>ne znayu tochno, mozhet, osnovnoe zerkalo pognulos' ili chto-nibud' eshe
Vikipediya pishet, chto tam oshibsya stre... to est', tehnik.
http://ru.wikipedia.org/wiki/Teleskop_HabblKomissiya, vozglavlyaemaya Lyu Allenom (angl. Lew Allen), direktorom Laboratorii reaktivnogo dvizheniya ustanovila, chto defekt voznik v rezul'tate oshibki pri montazhe glavnogo nul'korrektora, polevaya linza kotorogo byla sdvinuta na 1,3mm otnositel'no pravil'nogo polozheniya. Sdvig proizoshel po vine tehnika, osushestvlyavshego sborku pribora. On oshibsya pri rabote s lazernym izmeritelem, primenyavshimsya dlya tochnogo razmesheniya opticheskih elementov pribora, a kogda posle okonchaniya montazha zametil nepredvidennyi zazor mezhdu linzoi i podderzhivayushei ee konstrukciei, to prosto vstavil obychnuyu metallicheskuyu shaibu[11].
Kakaya zhalost'.
>Ne znayu. Zaderzhka sostavila by kak minimum 2-3 goda, no eto ne tak mnogo. Mozhet, eto kak raz byl politicheskii vopros.
Vot ya tozhe teryayus' v dogadkah: kakaya tut mozhet byt' politika, trubit' pro nepoladki edinstvennogo teleskopa, no dazhe ne popytat'sya zapustit' ego "blizneca" (a ved' tehnologiya otrabotana, i ih mozhno bylo by kak Vikingi shtampovat').
A esli by nepoladka okazalas' kriticheskoi (popadanie meteorita i t.p.)? Vse 17 let oni vprochem izbegayut popadat' v Habbl (v otlichie naprimer ot kompleksov Mir/MKS, kotorye imi probity kak resheto).
>Eto naivno. Pozvolyu sebe predpolozhit', chto vy ne rabotali s Habblovskimi dannymi.
Ya ne rabotal, no vopros tak skazat' ochen' vazhnyi. Esli iz kosmosa postupayut UF-snimki s poddel'noi PSF (Vy zhe sami pisali, chto eto vozmozhno pri uhudshenii kachestva, chto my i vidim na UF snimkah), to eto pozhalui nikak nel'zya raspoznat' (ne na chto operet'sya v sravnenii, t.k. net snimkov s kontrol'nogo kachestvennogo teleskopa). Hochetsya nadeyat'sya, chto u Rossii zapustit' takoi teleskop poluchitsya, tam ne budet "sluchaino 10-kratno isporcheno" izobrazhenie imenno v UF-diapazone i t.p...
- Re[8]: Kosmicheskii teleskop "Habbl"
(Dmitrii Docenko,
9.08.2007 13:38, 961 Bait)
> Znachit li eto, chto znachitel'naya chast' ploshadi zerkala prosto ne ispol'zuetsya, t.k. zakryta shel'yu?
Net. Zakryta znachitel'naya chast' fokal'noi ploskosti.
> Pochemu zhe togda imenno dlya spektrometra ne proyavlyaetsya ta nepoladka, kotoraya yakoby meshaet Habblu delat' kachestvennye UF-snimki?
"Nepoladka", tochnee, prisutstvie korrektiruyushego fil'tra, proyavlyaetsya v umen'shenii effektivnoi ploshadi, a ne uhudshenii uglovogo razresheniya. Kartinki ne stanovyatsya "razmazannymi", no pri tom zhe vremeni nablyudeniya men'she znachenie "signal/shum".
Na oba etih voprosa est' otvety v moih predydushih pis'mah. Samocitaty:
"Vmesto etogo fokal'nuyu ploskost' mozhno zakryt' neprozrachnoi plastinoi, ostaviv v nei tol'ko nebol'shuyu dyrku (obychno ispol'zuetsya shel', no ee mozhno predstavit', kak summu nakih dyrok)."
"Razreshenie u UF snimkov/spektrov otlichnoe. Effektivnost' malen'kaya."
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- Re: Kosmicheskii teleskop "Habbl" (T. R. taniyarajput483, 11.09.2022 10:00, 761 Bait, otvetov: 2) We guarantee a lively meeting that won't be your inspiration. We maintain premium categories of Greater Noida Call Girls in the most prominent areas of Greater Noida and South Greater Noida.
- Re[2]: Kosmicheskii teleskop "Habbl"
(pointedlynovell liu,
24.11.2022 5:54, 1.0 KBait)
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- Re[2]: Kosmicheskii teleskop "Habbl" (pointedlynovell liu, 24.11.2022 6:00, 93 Bait) 壯陽藥推薦
