Search found 828 matches

by oopfan
Sun Dec 20, 2020 8:24 pm
Forum: Gallery
Topic: Jupiter & Saturn, optimistic imaging
Replies: 14
Views: 633

Re: Jupiter & Saturn, optimistic imaging

As my stepmother would say: "It was one of my lesser successes" which revealed her optimism.

An excellent showing for 5 degrees above the horizon!

Brian
by oopfan
Sun Dec 20, 2020 6:30 pm
Forum: Tips and Tricks
Topic: A Scientific Approach to Narrowband Imaging
Replies: 5
Views: 670

Re: A Scientific Approach to Narrowband Imaging

Thank you, Dave. Excellent images! The Dumbbell Nebula is a planetary nebula, so we have access to its spectrum, courtesy of Professor Karen B. Kwitter, Williams College: https://web.williams.edu/Astronomy/research/PN/nebulae/index.php I've zoomed in on the area around the hydrogen-alpha (Ha) line: ...
by oopfan
Sun Dec 20, 2020 1:55 pm
Forum: Tips and Tricks
Topic: A Scientific Approach to Narrowband Imaging
Replies: 5
Views: 670

Re: A Scientific Approach to Narrowband Imaging

Robin, The only problem with the photometric method is that the ratios change with the bandwidth of the filters. For example, a 3nm Ha filter will isolate the Ha emission line, but a 7nm Ha filter will also capture two nearby NII lines. The NII lines are just as strong as Ha in some nebulae. The bes...
by oopfan
Sun Dec 20, 2020 5:39 am
Forum: Tips and Tricks
Topic: A Scientific Approach to Narrowband Imaging
Replies: 5
Views: 670

Re: A Scientific Approach to Narrowband Imaging

Hi Robin, Yes, the total integration time of SII will be seven times longer than Ha but only if we choose a long exposure for SII so that the per-sub SNR is the same as Ha. In reality this is impractical, so we need a longer integration time for it. Regarding light pollution, I am assuming that it i...
by oopfan
Fri Dec 18, 2020 6:56 pm
Forum: Tips and Tricks
Topic: A Scientific Approach to Narrowband Imaging
Replies: 5
Views: 670

A Scientific Approach to Narrowband Imaging

It is that time of year again for the Tadpole Nebula in Auriga. Last year was my first attempt at it. Sara Wager inspired me with her exceptional image using Ha and OIII. https://www.swagastro.com/ic410.html Like most people, I chose a single exposure and then captured an equal number of frames. It ...
by oopfan
Tue Dec 15, 2020 3:18 pm
Forum: General Discussions
Topic: Optimizing sharpness with SNR. DSO "lucky" imaging ?
Replies: 6
Views: 340

Re: Optimizing sharpness with SNR. DSO "lucky" imaging ?

Tim, I've held off from replying due to the word "DSO" in the title, but now that I see that the topic has shifted towards imaging stars, I can add something to the discussion. Feel free to use sub one-second exposures for the Lyra double-double. They are bright at 6th magnitude. If you ha...
by oopfan
Mon Dec 07, 2020 6:36 am
Forum: How do I?
Topic: Multistar FWHM and full-Moon sky brightness
Replies: 9
Views: 455

Re: Multistar FWHM and full-Moon sky brightness

Anthony, I know that some people swear by Bahtinov Masks, but I stopped using mine for two reasons: you need a bright star, and you risk accidental loss of PA putting it on and taking it off if you bump the tripod/mount. Also, I focus often, after slewing to a new object and after a filter change. I...
by oopfan
Sat Dec 05, 2020 5:10 pm
Forum: How do I?
Topic: How do I (can I) use SC to test ASI294 linearity
Replies: 15
Views: 656

Re: How do I (can I) use SC to test ASI294 linearity

Gary, I recognize the document in the screenshot of your original post: AAVSO's CCD Photometry Guide. I agree with Robin. You need a very stable light source. I tried an Electroluminescent Panel but found that the brightness varied. I ended up using an LCD monitor. I've attached results for a run at...
by oopfan
Sat Dec 05, 2020 12:38 am
Forum: Gallery
Topic: Guess the name of this large Lunar Crater with its central peak?
Replies: 1
Views: 282

Re: Guess the name of this large Lunar Crater with its central peak?

PYTHAGORAS

Geological period: Eratosthenian (From -3.2 billions years to -1.1 billions years)
Dimension: 129.0x129.0Km / 78.0x78.0Mi
Height: 4800.0' / 14500.0ft

Virtual Moon Atlas says that it is in the northwest quadrant, not southwest.

What do I win?
BTW, decent photo :-)

Brian
by oopfan
Mon Nov 30, 2020 4:09 pm
Forum: Gallery
Topic: An Oldie but Goodie: NGC7635 The Bubble Nebula
Replies: 6
Views: 358

Re: An Oldie but Goodie: NGC7635 The Bubble Nebula

Hi Bruce, Awesome image! For inspiration (and humiliation) I visit Sara Wager's website. Here is her rendition of the Bubble: https://www.swagastro.com/ngc7635.html Astro-Physics' website also shows a cyan bubble: https://www.astro-physics.com/ She did not specify, but I believe it is SHO. Plenty of...