The argument about Bias Frames

Until now I have not really used bias frames in my preprocessing (I attempted on the first few imaging attempts ever since I was told I should but quickly stopped using them). I decided to shoot some with my last imaging session and have been trying to compare whether or not they helped at all in the image. 

I did the exact same processing from stack to finish on all three variations except how the bias frames were applied. The first comparison set is just a center crop of M51 from my full frame.

-The first one has no bias at all
-The 2nd had bias frames preprocessed on both the flat and dark frames themselves as well as the preprocessing for the light subs 
-The 3rd had bias frames preprocessed on just the flat and light subs

So the 1st and 3rd appear identical (even when blinking between the two on a super-zoomed level) The 2nd seems the worst, which is what I suspected as I had been told if you add the bias to both the light and dark in Nebulosity it will basically add it back in. 

From this comparison (and the 200% crop) it really almost doesn't seem worth it.


However, since I posted this observation on various astronomy forums I frequent I have all but gotten "shot at dawn" as one guy so eloquently put it. I have been told that flats WILL NOT work if you don't apply bias frames to them (interesting since I have not used bias frames since I started imaging and my flats have been working perfectly well) ... I have also been told that I really only need them if I am going to use scaled darks, which makes much more sense to me than the "nothing will work right if you don't use them" argument. 


Seeing as they take almost no time to shoot and add into my pre-processing steps I might as well use them to avoid further ridicule but seriously - see if you can really tell a difference in these 100% and 200% crops of the M51 image I am currently imaging. 

Also, according to Ron Wodaski's "The New CCD Astronomy", pg 244: 
"The sole purpose of a bias frame is to allow you to use dark frames whose exposure time does not match the light frame exposure time. If you always take dark frames with the same exposure as your light frames, you do not need to take bias frames" .... 


Since I don't use scaled darks this explains my results and I am officially ignoring all the contradictory and argumentative (& some downright rude) comments I have been getting to this question on my astronomy forums. 

December 2010's total Lunar Eclipse

As it would so happen, I moved out of the US just before the total eclipse of 2010. Amidst the clouds and current snowy/icy weather in England I was not expecting to be able to see anything, especially coupled with the fact that here in England totality would begin just before the moon set and the sun rose for the day - what timing!

It turns out I lucked out bright and early on the morning of the 21st as it was unusually clear in the sky, albeit incredibly cold. I was able to see the eclipse start and went out every 10 minutes or so until totality. Just as dawn brightened the sky I was able to watch the moon completely disappear into the shadow of the Earth. Unlike my counterparts in the States who would get to see a lovely red color to the moon during this, I literally just got to watch the moon disappear - it was pretty neat.

My telescope and tripods are all currently packed away as we still havent moved into our new place, so I just shot a few handheld images throughout. No fantastic shots, but at least I was able to document the first total lunar eclipse to fall on winter solstice in more than 400 years!

Click here to view my Eclipse sequence larger

Comparison of 1st year of astrophotography

What can you learn in your first year of astrophotography .... well, a picture (in this case 6) is worth a 1000 words .... Here is a comparison of my very first astrophotos, fully processed to my abilities when I took them on the left one year ago to the ones I took over the past month and fully processed.

Make sure you view a Larger Version so you can see just how awful my first ones were :-) (though at the time I was happy that I was getting anything)

Yes, I have upgraded equipment, which definitely helps, but technique and processing skills have greatly increased as well.

I have cropped and adjusted the scale so they are comparable in size for comparison purposes, otherwise, no additional editing was done on the photos from my processing a year ago (ugh!)

This comparison just goes to show what a learning curve this hobby has and how much progress you can make in just one year if you keep at it! Hopefully this can encourage some of you just starting out and getting frustrated with what you are getting compared to those who have been doing it for many years!!!

Finally back into the night

Its been a few months of clouds and rain and so I havent gotten to get out to observe or image in quite some time. My local astronomy group (San Antonio Astronomical Association) had an outreach outing at Garner State Park this past weekend and the forecast was iffy, but had the possibility to be nice so I packed all my gear and drove out for it. We were treated to a gorgeous night free of clouds until around 245 in the morning. Each scope had lines of people, adults and kids alike, excited to see planets, globular clusters, nebulas - basically whatever we would show them. It was a great time.

About 11 pm the crowds left and I was able to start imaging. I had already selected the Trifid Nebula so retweaked my alignment since it had gotten bumped with all the people around the scope and began imaging. I got a good amount of Luminance, Red & Green data. I had just started the Blue channel when the sky got completely socked in. Once I got home the next day I ran through my normal processing except I had to take the two blue frames I got before the clouds and some tweaking with the Green channel to create a false blue to see what I had ... despite the false blue channel, I am happy with the result.

I do plan to get out and get some proper blue sometime soon, but for my first chance at imaging since April, it made me happy to be back out with the scope.

Behind the scenes, at NASA!

Earlier this week my husband and I were fortunate enough to attend NASA's latest Tweetup at Johnson Space Center. What is a Tweetup? Well, it is a gathering of Twitter followers of course. NASA has been putting them on recently to gain publicity and awareness of launches, programs, etc. Myself (@antimorris) and my husband (@vtmath) traveled the short distance to Houston for a full day at the home of astronaut training, Johnson Space Center.

We were greeted with nametags, coffee, and an hour or so to explore the Visitor Center before it was open to the public. It was very nice to see the exhibits without the noise of crowds and enthusiastic children (although I think all of us at the Tweetup were just as, if not more, enthusiastic about this than all the children!) ... after the initial free-time we all gathered in the auditorium for some briefings. These, mind you, are not your typical boring briefings. We were treated to a backdrop of the live EVA going on up on the ISS and talks from astronauts Ellen Ochoa & Jeff Williams as well as a very in-depth break-down about the new Ku-band communications antenna that was being installed by the EVA in the background. All of these "briefings" were very much audience focused and the majority of the time was spent on Q&A rather than just being talked at. I think we all thoroughly enjoyed Jeff Williams (@Astro_Jeff) describing the differences in launch and landing in the Soyuz versus the Shuttle, just how excited all the astronauts are that they now have internet up on the Space Station, and their new exercise equipment up on the ISS. 

We then had time for a quick lunch in the VC cafeteria and then broke our 100 person group into two to start the tour. This was, mind you, not the typical tour you get when you visit JSC! We first headed over to Mission Control ... yes, THE MCC which was currently running STS-132. We got to sit in the gallery and watch them finish up the EVA and have Ed Van Cise (@Carbon_Flight), a Flight Director for the ISS, speak to us.

If this wasnt enough, we then made our way through the labyrinth that is Building 30 down to the historic Apollo Mission Control. Why Annie, you might say, the Apollo Mission Control is on the regular tour. Well, yes, and no. Normally you get to go to the gallery for the Apollo MC and just look in the room, we got to go in the room, press buttons, sit in the Flight Director's chair and wave back at the people on the "regular tour" in the gallery. It was fantastic!

This day couldnt get any better, right? .... WRONG! Where we headed to next was the place I have been wanting to see for years and was the most excited about (although MCC was pretty darn neat!) ... The Neutral Buoyancy Lab (NBL)! Thats right, the ridiculously giant, perfectly clear swimming pool with life-size shuttle cargo bays and the ISS in parts in it so astronauts can train on them. To make it even better, there were multiple astronauts in the pool (each with 4 safety divers) training when we were there. This massive training facility is beyond description. The only thing that would have made it better was to have been able to go diving in the pool, but alas, only NASA-certified divers are allowed.

By this point, I am beyond a happy camper. But we are still not done with the tour! We next head over to the Space Vehicle Mockup Facility (SVMF) to see the shuttle, Soyuz, and ISS trainers. We, of course, get an astronaut tour-guide, Dave Leestma, and also get to see STS-133 crew as they practice their post-liftoff suiting procedures. In this building they also have the new Lunar Electric Rovers, and some other robotic prototypes for future space operations. All very neat to see. 

We then capped off the day with a visit to the Rocket Park and the Saturn V rocket, which I have seen many times but am still impressed by its size every time I do. 

My overall impressions for the day ... WOW ... oh and never did I think that Twitter would be so useful. Getting to watch Mission Control run a shuttle flight, see astronauts train in the NBL, chat with multiple astronauts, and everything else we did were just amazing. Thank you Johnson Space Center and NASA for the behind-the-scenes look at everything. As someone described during the day, it was like having the golden ticket to get a special tour of the Willy Wonka's chocolate factory. It was a fantastic day and I really hope that we are fortunate to do another Tweetup with you in the future (preferably to a shuttle launch, hint hint)

Click on any photos here to see them larger or if you want to see all of my photos from the day, they are located here: STS-132 Tweetup Photos