More DMK 41AU02.AS First Light Images -- the Sun

Blogged by Jonathan Maron on August 29, 2008 and tagged with Sample Images, Sun.

Over at the Sunnymeade Astro Blog, Mark Walters has posted a detailed account of his first experiences, using a new DMK 41AU02.AS. He writes:

The DMK 41AU02.AS USB camera arrived yesterday. At 1280×960 resolution this should theoretically be able to display the whole disk in IC Capture and allow single videos of the surface and proms to be taken which can be combined without having to laboriously stitch panes together. First light today proved that this is indeed the case. It was great being able to see the whole disk on the screen. Until I zoomed out I was scrolling a lot to see which edge was passing out of frame view first, but zooming out made this easy to judge so that the disk could be centred on the chip for best overall focus.

Having found the optimum settings for prom and surface capture I saved these configurations specifically for the DMK 41AU02.AS as the DMK 21AU04.AS configurations cannot be used and result in an error. A video of 2000 frames produces a file size of 2.28 GB in just over two minutes at the 1/15 sec max capture rate. In Registax 4 I came up against the problem that Registax will only recognise AVI files up to 1GB in size which equals 869 frames. Beyond that Registax throws up a read failure message and the aligning procedure fails. So until registax 5 comes out I may be limited to videos of 869 frames, which isn't too bad, but I would prefer to be able to stack at least 1000 to reduce noise in the final image. K3CCD Tools may be the answer to my problem but an early attempt to stack in that resulted in confusion - I need to read the manual !

The whole disk view does seem to show up the shortcomings of the PST now though. It appears my PST may be slightly astigmatic with focus better on one half of the sun than the other. This is really obvious now whereas with the smaller DMK 21AU04.AS each pane was capable of being sharpened so that the overall view looked more consistent. Sharpening the whole DMK shots does look OK though and the inconsistent focus may even be due to the chip not being square to the objective in the holder - need to check that!

Today was not exactly the sunny, blue-sky day that was promised by the weather forecasters! We actually got 1 hour of patchy clear sky then thick cloud the rest of the day and rain in the evening. I captured these images at 9.16 UT. Not much to see in terms of proms, but the active region is a little larger and there were some small filaments around. Overall i'm pleased with the speed at which I can create a high resolution full disk now and will be even happier when Registax 5 comes along !

Below are three photos which he uses to illustrate the text (click to zoom):

Mark, I can only commend you for these great first light photo!

Keep up the good work and send us some more of your great work! :-)