1.91
#... |
|---|
|
Ok guys. This is quite an unexpectedly challenging object. Here is a blend from 12 / 5 minutes subframes per CLS and H-alpha channels. Clouds were moving in at high altitude, which reduced transparency to around 2/5 and likely influenced the lack of contrast. Nonetheless, the surface brightness of this nearby irregular dwarf galaxy spread out in a wide field of view and makes it quite difficult to get enough SNR in a short amount of time. My telescope is F5.4 which is reasonably fast but surely not enough to get enough data in one night. Any tip or advice is highly appreciated from those who have captured this faint galaxy with relative success under suburban skies. What total acquisition time is suitable in each CLS/Ha/OIII/SII channels? Should I try with 10 minute subs instead of 5 min.? Thanks Guy https://astrob.in/1qes69/0/ |
1.91
#... |
|---|
|
Hi I haven’t imaged this particular galaxy yet, but have done other faint targets. If your sky conditions allow, increase the exposure time. Use RGB filters, not Oiii or Sii. Only use Ha if the galaxy contains interesting Ha regions (search here on astrobin). And finally, use a much longer integration time. If you have light pollution, you need to increase the integration time in order to get rid of the extra noise. Good luck |
|
1.91
#... |
|---|
| Thanks for your advice. Yes, this object has HII regions all over the place. I might take extra exposure time on Halpha and add some SII to the mix. Probably an entire night dedicated to this red shifted end of the spectrum. Maybe another night for more CLS. Not sure about RGB, I mean I am under Bortle 7 skies and things can get messy. I will try the 10 minutes single exposure times to see if at least I can get rid of read noise and definitively consider another two extra nights on this target. Now I will have to wait for the clouds to clear (rain showers expected for the next 4 days here in central Chile). Well, enough time to plan this ahead of time. Thanks again! |
