The Starry Night, 65

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10/2/2011. Another cool, clear night with slightly better seeing. I saw PSF's around 2 - 2.4 arc seconds but got finished images around 3.5. Something about the guiding settings is causing the 'scope to chase seeing and go a little crazy. Increasing guide integrations to 4 seconds and allowing dec corrections in only one direction helped. I started with a sanity check on M13 (OK but nothing special, not worth spending your bandwidth, hence omitted here), then spent some time gathering color data just south of NGC 6995, the bright knot at the south end of the larger arc of the Veil. Images with the 5-inch refractor last year suggested that this might be an especially interesting area to inspect more closely. Seeing and guiding improved during the RGB collection period so I finished with an hour of luminance. And finally, I left the kit to collect data on M31's V1. Five minutes was sufficient to show the variable, but I collected light for 3 hours to get a clean signal.



NGC 6995

Detail of the Veil, south of NGC 6995
2x900s RGB, 4x900s L


m31 v1

V1 in M31
36 x 300s L


All these images were made with the ST2000XM cooled to -30C. Shortly after sunrise, the CCD was holding that temperature with only 65% cooling and could (just barely) hold -40.

I need to revisit the Veil under steadier skies; V1 seems decidedly brighter than just a few days ago. I need to devote an hour or so to this field at every opportunity for the next few months to see if I can get a decent light curve.


10/4/2011. I tried for an exoplanet (TRES-3 in Hercules, the relatively deep and very quick transit of a hot Jupiter in front of a 12th magnitude star). I had just taken the OAG apart and reassembled it and did not have time to get it readjusted when the transit was upon me. (Details of the OAG adjustment are on page 56.) So I left the telescope to track this on its own and went off to watch a Ken Burn's documentary with Amy. The individual frames (30s) were plenty sharp, but over the course of two hours, the field walked off the chip and I had to toss the whole series. The transit began in deep twilight, and that, too, led to problems. Tonight's lesson: you can do exoplanet transits, but you can't be this casual about them.

I finished setting up the OAG and collected more luminance data to improve the image of that bit of the Cygnus loop shown above. When M31 emerges from bird feeder tree, I'll set up the telescope to take another data point for Hubble's V1.

Here's the difference good seeing (focus to 1.4 arcseconds, achieved PSF 2.2) and proper guiding (sub arcsecond corrections) make:


veil detail

Detail of the Veil, south of NGC 6995
7x900s L, 2x900s RGB


Under the western wing of Cygnus, between 5 and 10,000 years ago, a supernova went off and scattered the material of its progenitor star far and wide. In this photo, the shock front from that explosion (travelling several hundred or a few thousand miles per second) is meeting and mixing with the interstellar medium. The iron in your blood, the nickel in your pocket, the gold that used to be in your IRA, the oxygen and nitrogen in the air, the carbon in your DNA -- virtually everything heavier than hydrogen and helium -- was formed in a star that was torn apart in an explosion like this before the Earth and the Sun took form. This here would be a photo of darkness on the face of the deep.




Starclouds (and V1) in M31
21 x 900s L, 1 x 300s RGB


Refer to the image up top to find V1. I'm intrigued by the clarity with which drifts of bright stars in brilliant associations in M31 are rendered. When the air is still, reasonably clear, and the guiding is spot on, things become visible. I've taken advantage of calm air to collect a lot of luminance data; I can add more RGB when the seeing is much worse. We're getting on down toward 20th magnitude here.


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                   © 2011, David Cortner