Monthly Archives: January 2014

Trapezium Project – 2014-01-22

Imaging the trapezium – the multiple star cluster at the centre of the Orion Nebula (M42).

Equipment:

Scope: EdgeHD 11 (focal length 2800mm, f/10)
– astro-tech diagonal (too cold to refocus for straight through config)

Camera: Canon T2i modified with astrodon UV/IR filter
– Pixel pitch advertised as 4.30 um
– Width: 22.30 x 14.90mm
– Active Pixels: 5184 x 3456
– Astro SW though uses 5202 x 3465 pixels.

Mount: CGE Pro
– unguided, no PEC, PA hasn’t been done in awhile

I calculate the resolution of this optical train as 0.32 arc-sec per pixel.

However, a platesolve using Platesolve2 (by Dave Rowe) and the UCAC3PS catalog results in a resolution of 0.266 arc-sec per pixel.

From a run last year with the HD11, 5x powermate and a chameleon webcam i got this result:

Trapezium with 6 members resolved

Trapezium with 6 members resolved – 2013-04-01

 

The table below are the stacked versions of several different exposures.
– The picture is a tight crop of just the trapezium with a moderate stretch. Something akin to what the camera does for a non-linear jpg.
– The platesolve is the result of the platesolve2 on the fits file.
– the fits file is the full frame of a the stack of the calibrated and aligned lights for that exposure. The data is linear 16bit RGB.

To download a .fits files, right click and select “save as”. (Clicking on the link just opens up the .fit file as a text file, which isn’t any good at all.)

Note that all fits files are align to the same master. So its possible to combine the individual exposures into an HDR.

trap_1x4s_iso400.fit
integration: 4 * 1/4sec at ISO400
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB
trap_1s_iso400.fit
integration: 2 * 1sec at ISO400
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB
trap_2s_iso400.fit
integration: 4 * 2sec at ISO400
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB
trap_3.2s_iso400.fit
integration: 5 * 3.2sec at ISO400
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB
trap_5s_iso400.fit
integration: 5 * 5sec at ISO400
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB
trap_10s_iso400.fit
integration: 6 * 10sec at ISO400
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB
trap_30s_iso400.fit
integration: 5 * 30sec at ISO400
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB
trap_30s_iso800.fit
integration: 7 * 30sec at ISO800
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB
trap_30s_iso1600.fit
integration: 6 * 30sec at ISO1600
pixels: 5202 x 3465
format: RGB, 16bit unsigned int
Download size: 105MB

Observing Report – 2014-01-14

After 8 weeks of almost no astronomy, i finally opened up the dome. In truth, i did take out the 3″ refractor a couple of times for a quick peek at things from the front porch. But for the last 2 months it’s either been cloudy or there was a full moon when clear so not worth getting out the big scope. There were 2 decent clear nights, but social engagements precluded spending an evening in the observatory.

Pyroclastic formation south east of Mare Vaporum

Pyroclastic formation south east of Mare Vaporum

On Jan 14th there was also an almost full moon. But i had a specific objective for looking at the moon when full. When doing a little research for my image of the pyroclastic formation near Mare Varopum, i found a reference that stated the dark pyroclastic formation could even be seen at full moon.

The forecast was for clear skies in the late evening with moderate to poor seeing. The skies were clear and quite transparent and the seeing on occasions was actually 4/5 – but only for a few seconds at a time. Mostly it was the predicted poor 2/5.

Using the HD11 and 24mm Hyperion (mag 116x and 35′ real FoV) i first checked out the double in Rigel. At first the glare from Rigel obscured the companion. But when the seeing stabilized, it was easy to see.

Betelgeuse was a beautiful orange. I half expected it to go supernova while observing it. It’s reported to be quite unstable and ready to explode sometime between now and the next million years.

Just for fun, i slewed to Alnitak – the left most star in Orion’s belt. And then down a half a degree to where the horse head nebula is. Of course i could not see it as it’s really an HA object and only visible in HA capable cameras.

trapezium 6 starsThe next target was the Trapezium in Orion’s sword. It’s at the centre of the Orion Nebula (M42). The centre of the nebula is visible in an EP as a distinct grey patch with well defined edges. Averted vision affords some structure to the otherwise smooth “cloud”. The 4 stars that form the bright trapezium – mag 4.96 to 7.46 – were of course obvious as the separations vary from 9″ to 19″. After a few minutes of observing, i also detected a 5th member – E – which is mag 10.3 and positioned between A and B. The 6th member F is mag 10.2 and should have been visible, but i did not see it. To my credit, i did not know where E and F were located, so the observation is by merit alone.

The image below captures what it’s like to try to see the faint E and F members. The tear drop shapes are due to atmospheric dispersion as the image was taken when Orion was quite low in the sky. (Note that this image is flipped relative to the graphic above.)

Trapezium with 6 members resolved

Trapezium with 6 members resolved – 2013-04-01

I took a quick look a Jupiter. The seeing wasn’t very good at the time so i could not make out any details expect for the major bands. There were 3 moons visible at the time of observation at about 9:30. These were Io, Europa and Callisto. Had i waited just a few more minutes, i would have seen Ganymede emerge from behind Jupiter.

The last target was the full moon. Even with a 10% neutral density “moon” filter, it is blindingly bright. After a few minutes to orient myself and get used to the flipped horizontal view with an SCT and diagonal, i was viewing Mare Varporum. The ridges on the formation of interest were just visible as bright jagged lines. I could not detect any darkening in the region even though at other lunations, this region is distinctly reddish in colour.