First Quarter
Category: Astrophotography
Peering into the dark with a camera
Control
Postcard from the Universe – Orion Nebula with the EOS-M
The first astrophoto taken with the EOS-M. Considering the trouble it is to manually trigger the exposures without proper camera control, I am surprised I stuck it out to take 40+ subs. Since 30 seconds was the longest I could program the camera for I simply maxed out the ISO and took a lot of subs plus a dozen darks. There is still way too much noise in the resulting frame. Still, the ISO 12,800 frames are not all that bad, better than I expected. If this camera had remote control it would be a decent little astro camera. Longer subs and a lower ISO would deliver decent results.
Astrophotography with the EOS-M
In the few days I had the camera I was determined to acquire some astrophotography test shots with the EOS-M camera. Even if it meant getting up at 3am to have some dark sky after moonset. It would have been easier a few days before, but a Pacific storm system had provided several days of overcast with occasional rain. This particular morning was just about perfect, clear skies, decent seeing and no wind to bounce the telescope around.
The result is an f/7 optical system with 1080mm focal length. This gives a field of view of about 72×48 arc-minutes (1.2 x 0.8 degrees) on the sky when using a camera with an APS-C sensor.
A Cometary Breakup
While Comet 168P Hergenrother may be a bit of a mouthful, it is the proper designation for an interesting comet. Discovered in 1998, the comet is one of dozens that orbit in the inner solar system. Normally inconspicuous objects, these comets orbit quietly, objects that only astronomers love, or even know about. You would normally have needed a substantial telescope to see 168P, shining very dimly at magnitude 15.5 at it’s brightest. A community of amateur astronomers keeps tabs on these comets, occasionally photographing them, updating the orbits.
As the comet approached perihelion during the beginning of October, it became apparent that something had happened. Several observers were reporting that the comet had brightened. Suddenly the comet was far brighter, eventually reaching near 8th magnitude, over 500 times brighter than expected. We have seen this sort of thing before, a cometary breakup. Observations from several large telescopes, including Gemini North here on Mauna Kea, showed that the comet has split into at least four pieces.
When a breakup occurs it exposes a great deal of fresh material and debris, dramatically adding to the supply of dust and gas in the coma and creating a far brighter object. It is not the comet itself we see, that is fairly small. It is the coma and tail, the cloud of dust and gas that reflects the sunlight and gives a comet the synonymous appearance.
Comet 168P Hergenrother currently sports a small fan shaped tail, easily visible in the telescope. We enjoyed this classic comet shape in the telescopes last new moon at the Mauna Kea VIS. Setting up a telescope and CCD camera last night allowed me to photograph the comet, appearing much the same as it did a few weeks ago.
Postcard from the Universe – M22
The seeing was pretty bad, leading to bloated stars in the image, unusual conditions for Hale Pohaku. Still a nice subject for the AT6RC and 60D camera. I expect I should shoot this target again.
Astrophoto Interference on Mauna Kea
Mauna Kea is simply a great place to shoot astrophotos from. Dark, clear skies with typically good seeing. Unlike some mainland locations there is a distinct lack of aircraft overhead. I am not sure how many shots I have had ruined by the bright anti-collision strobes crossing through the frame when shooting from locations in Arizona.
There are hazards to shooting photos here that do not commonly exist elsewhere. I was unpleasantly surprised when reviewing the take the next morning to find brilliant yellow lines through a hour and a half of exposures taken of the Cygnus region. The material is otherwise great, the makings of a nice shot, except for this one little issue. There are ways of suppressing artifacts like this when processing, but the beam is so bright I am not certain they will work all that well.
Worse, I checked the schedule, the offending laser is coming from Keck 2 AO, a system I work on.
The observatories have a system in place to deal with this issue. There are four operational lasers on the mountain, Keck 1 and Keck 2, Subaru and Gemini. Each optical observatory using a laser maintains a server that posts their laser location, status, and calculates the position of each beam in the sky. This can be queried by the other observatories to check if the beam crosses the field of view. A set of rules has been negotiated to determine who has right of way, usually who is on target first.
Obviously this computer system does not take into account my little telescope shooting photos from Hale Pohaku. If I had known I could have called Heather and asked her to shutter her laser, I was on target first. Being the kind soul she is, she would probably laugh with me.
Postcard from the Universe – Galactic Center Grande
On request I am publishing a larger version of my galactic center shot. I really do need to re-shoot this with an Hα sensitive camera.
As usual, click on the image for the larger version…
Postcard from the Universe – Butterfly Cluster
Known as M6, NGC6405, or The Butterfly Cluster, this pretty open cluster lies just above the tail of Scorpius. Visible to the unaided eye under a dark sky, it is an easy photographic target.
I have been working on improving the color balance in my astrophotos. Color is an interesting and complex subject in photography, worse in astrophotography. I think the results are much better here that in my previous work. Hope to take a few more photos this week and will continue to experiment.
Postcard from the Universe – Galactic Center
The last time out I fitted a camera ball mount to the counterweight shaft of the Losmandy mount. This allowed me to shoot an additional camera at the same time, along with the camera attached to the telescope. The second camera can be aimed at a different target completely. With a relatively wide angle lens, tracking errors become insignificant.
With the center of the Milky Way high overhead it made an obvious first target to test this wide-field setup. The results are quite nice, a series of one minute exposures reveal the star clouds in fine detail. The camera for this run was the Canon 60D, as the 20Da was shooting the Lagoon at the time. I need to swap places and try the shot again with the 20Da to see what the Hα sensitivity reveals, capturing more of the nebulae that is mingled with the stars.
The lens was an older Nikon 50mm f/1.8 stopped down to f/2.8, nice round star images right into the corners of the frame. Yes, a Nikon lens mounted to a Canon camera, you can do that. A very nice lens, I will be using it again for this work.
