On the 28th November I setup early for a full night of imaging. Within an hour and a half the scope was assembled, aligned, collimation checked and drift align complete. A couple of minutes later and the CCD and guide camera were attached and I was back indoors with a nice warm drink and focusing the main camera.
That’s when the issues began. At first I thought it was just the Olimex A20 losing its wifi connection. After multiple reboots, adding a wifi extender and trying a better dual antenna wifi adapter, the A20 stopped completely. Not a wifi issue after all.
I then realised how far the temperature had dropped. The nights forecast for 1 degree was a little off. The temperature had dropped towards -5c, too low for the Olimex (apparently all components are rated to -20c other than the RAM which is 0) and as the device had been idle for quite a while it had failed to keep the dry box internal temperature above freezing.
I swapped the Olimex out for the Raspberry Pi 3 I’ve been using to test the new astro hat along with the hat itself to act as a 12v to 5v supply for the Pi and was back up and running.
The next issue to hit was fogging of the corrector plate, despite a relatively high setting on the dew heater. In the end it needed 90% power to keep the scope clear.
Then began the guiding issues. RA guiding alone was good but the Dec drift required guiding in two axis and the moment Dec was turned on, the guiding graph went all over the place. Eventually I managed to get reasonably stable results by turning on dec guiding in a single axis only but it was far from ideal.
I’ve since read up on the guider’s PID settings and will be tweaking those during the next session. I’ve also tuned up the Dec drive which had developed a little too much play between the gears due to a screw that the worm gear pivots on being a little too tight.
Despite all that, several hours later and nearing midnight I was finally able to start collecting some reasonable data on a few targets. I focused mainly on M1 the crab nebula, then took a few exposures of M76 and M78 to help gauge what a future session would need to dedicate to imaging those.
M1 - Crab Nebula
|Exposure Time||11x180s and 13x120s|
|Date||2016-11-29 01:00 UTC|
|Bias/Dark/Flat Frames||41x0.001s / 10x120s / 53x0.13s|
The image was processed using PixInsight which I’ve just started to learn my way around. Considering the conditions, guiding issues and a shorter session than planned, I’m quite pleased with how well this image turned out.
As far as supernova’s go, the results of this one are quite spectacular and a mono image just doesn’t do it justice. Whilst having the honor of being the first fuzzy blob to be catalogued by Charles Messier, this object was apparently seen as far back as 1054 by Chinese astronomers.
Chinese astronomers watching the sky on July 4, 1054, noted the appearance of a new or "guest" star just above the southern horn of Taurus. But knowledge of star-fields was not necessary to spot this surprising visitor — according to records, the bright source was visible during the daytime for 23 days, shining six times as brightly as Venus.
M76 and M78
The next two targets, M76 and M78, didn’t turn out as well.
I collected insufficient data for both of these but especially for M78. With exposures of 41x60s for M76 and 9x120s for M78.
Despite this, the general shape of the M76 nebula and central star can just about be made out.
I’ll have to return to these another night and try again.