Diffraction Effects – 18 May 2009

Location: at home in Tomball, TX
Cloud cover: 0%
Transparency: above average (4/5)
Seeing: est. avg (3/5)
Darkness: no moon, city glow
Wind: light, less than 5 mph
Temperature: 65º+
Humidity: 45%-60%
Dew Point: 45º-55º
Time: 9:00 pm – 10:15 pm CDT
OTA: 8″ SC

Started by observing M13. Some faint individual stars appeared in averted vision. Seemed larger apparent diameter than other GCs I recall.

Next stopped at Saturn. Rhea and Titan were easily visible. Two stars (mag 10 and mag 12-13) also in the field that I mistook for Iapetus and Dione (respectively).

I wanted to spend some time observing an airy disk to estimate seeing conditions. I started with Arcturus. Very bright center, yellow-orange color. Ring pattern was usually discernible. Focusing was somewhat challenging due to variations in distortion. Radial streaks or spikes also visible. Needed 7.9mm ep to observe diffraction rings.

Also noticed there was a diffraction line across the entire FOV when using the 45º erecting prism diagonal. Line appeared with different EPs, did not appear with 90º reverse-image prism diagonal.

Finally tried observing airy disk for Spica. Blue color was striking contrast to Arcturus’ yellow-orange. Observed similar variations and distortions of airy disk as observed with Arcturus. Also noticed that the tips of the radial spikes in one direction had an orange tint. I moved the star across the FOV to see if the effect was an off-axis abberation, but the orange tips retained their orientation independent of Spica’s position in the field. Spica was about 45º altitude, so it didn’t seem like it would be an atmospheric effect. My other guess was that Spica might be a double star and that the secondary might be spectral type G or K. A quick google search shows Spica is indeed a binary double, but I haven’t yet found any info on the separation or the spectral class of the companion.

I’d say the seeing was about 4/10 on the Pickering scale, often varying between 3 and 5.

Full of Stars – 22 April, 2009

Location: at home in Tomball, TX
Cloud cover: 0%
Transparency: n/r, est. average (3/5)
Seeing: n/r, est. poor (2/5)
Darkness: no moon, city glow
Wind: light, less than 5 mph
Temperature: 75º+
Humidity: n/r
Dew Point: 45º-55º
Time: 8:45 pm – 10:00 pm CDT
OTA: 8″ SC

ε Boötis DBL very close pair, cannot split in 12.5mm except in rare moments of good seeing (poor seeing generally), appeared as oval with red and blue sides. completely blurred in bad seeing.

M81 GAL UMa very faint fuzzy with no detail.

ξ Boötis DBL est. mag 4 white and mag 5 orange, close pair easily split in 12.5mm. Wikipedia lists ξ Boötis A as 4.5-4.7 G8 variable and 7.0 K4.

κ Boötis DBL est. mag 4 blue and mag 5 /yellow, close pair easily split in 12.5mm. Wikipedia lists them as 4.5 A8 and 6.6 F1.

M3 GC west of M13 (which was behind the house in the NE ) – wide fuzzy, no individual stars visible.

Mizar DBL est. mag 2 blue and 2.5 white. close pair easily split in 12.5mm. Wikipedia lists them asmag 2.2 A1 and mag 4 A7.

Cor Caroli DBL est mag 2 blue/white and mag 3.5 yellow/green, another easy split. Wikipedia lists them as mag 2.8-3.0 variable A0 and mag 5.5 F0.

My estimates were much worse tonight than last night, especially the secondaries.

Live Cam Limitations – 21 April, 2009

Location: at home in Tomball, TX
Cloud cover: 0%Transparency: average (3/5)
Seeing: poor (2/5)
Darkness: no moon, city glow
Wind: breezy 10-15 mph
Temperature: 70-75
Humidity: 52% up to 64%
Dew Point: 50-60
Time: 8:30 pm – 10:30 pm CDT
OTA: 8″ SC

Used Live cam to image Cor Caroli (DBL) and Saturn. Live cam does not appear to have as much clarity as the NexImage; images are fuzzier. Still post-processing image data for publishing.

Cor Caroli taken with Creative Live Cam through Celstron 8" SCT under poor seeing conditions. 91 total frames aligned and stacked.

Also observed Saturn visually. Titan, Rhea, and Dione formed a nearly equilateral triangle off one limb of the rings, Tethys orbited outside the other limb. Iapetus still at relatively small separation from Saturn.

Saturn and five of its moons taken with Creative Live Cam through Celstron 8" SCT under poor seeing conditions. Two separate exposure settings for Saturn and for its moons. 253 total frames, aligned, stacked, and heavily processed.

M40 DBL in UMa faint and unremarkable, approximately equal magnitudes.

M85 GAL in Com appeared as a very faint fuzzy.

Algorab DBL in Cor – easy split, guessed delta mag 4 or 5. SNP lists Algorab as 2.9, doesn’t show companion or even indicate Algorab is a double.

24 Com – yellow primary, blue secondary. Guessed magnitudes 4 and 5, SNP lists them as 5.0 and 6.6, but online reference listed them as 5.2 and 6.5. In fact, I’ve noticed that researching star magnitudes online there is a lot of variability inthe magnitudes reported for most stars. Not sure what to make of that yet.

Polaris photo test – 20 April 2009

Location: at home in Tomball, TX
Cloud cover: none
Transparency: above average (4/5)
Seeing: poor (2/5)
Darkness: no moon, city glow
Wind: none
Humidity: 75%
Temperature: 60° F
Start Time: 10:30 pm CDT
End Time: 11:00 pm CDT
OTA: 8″ SC

The Celestron NexImage camera has stopped working. I emailed Celestron customer support, but they have not contacted me, so here I have clear skies and no camera.

I recently found a webcam capture utility for Linux called webstream and decided to try it with the Creative Live web cam I bought on clearance last year. The goal for the evening was just to step through an entire cycle of image capture and stacking to verify that it could be done.

When I first tried using the Creative Live cam last year the I was disappointed and frustrated because the Windows driver would BSOD within a minute or so of operation. I tried it in three different machines with the same result. I hoped the linux driver might work better, and it did. Installing the driver, however, was no picnic. In fact, just locating the driver was no picnic. The camera model was not supported by the standard gspca and uvc linux webcam drivers. After more than an hour of googling I found driver source code, built it, and the world was happy (well, in any case the camera owner was happy). I captured a quick picture from my desktop just to verify that it was waorking correctly with camstream. The first step was successful, but how would it do as a cheap astrophotography camera?

Before mounting the camera to the telescope I removed the tiny webcam lens. It unscrewed easily. I assume that like many webcams the lens had an IR filter, which means that star images captured without the filter will appear brighter than in visible light. Next I used a rubber band to wrap the webcam’s round plastic cover. With the rubber band in place, the camera fit snugly into an old 1.25″ barrel I recycled from one of those useless 4mm eyepieces bundled with a starter scope. Now I was ready to mount it in the telescope!

I set up the scope on the driveway and aimed at Polaris. All the camera adjustments (gamma, brightness, saturation, etc.) were set in the “middle” of the slider range. There are no numeric indicators or fine controls in camstream, so I could only estimate. After the camera was configured I could see Polaris as a bright, flickering disk and I could almost make out Polaris’ brighter companion on screen. I was disappointed that camstream had no shutter speed control, nor could it capture images faster than one per second. I grabbed a few dozen images and shut everything down. The second step was successful, so far so good.

Next I copied the images up to my desktop and opened them with Registax. I recently upgraded to a newer version and I spent a few minutes learning to navigate the new interface. For some reason object tracking was not selected by default. Anyway, it stacked the frames and eliminated the noise. Unfortunately Polaris’ secondary was too dim for Registax to pick it out from the noise. Polaris itself looked a little distorted, but the seeing was poor and the star is only 30° altitude, so I didn’t expect much. As far as I was concerned, the third step and the entire night was a success.

So how does the Creative Live cam compare to the NexImage? Well, they both have a resolution of 640×480, so no big difference there. The sensitivity seems pretty comparable. Last year I imaged the Trapezium with the NexImage and θ1b Orionis (at mag 8.0-8.5) was just barely visible. Various sources list Polaris B between mag 8 and 9, slightly dimmer than θ1b Orionis. The Live cam was able to pick up Polaris B, but at the noise level. The cost difference is pretty big: you can get the Creative Live cam for about $16, but the NexImage is $100. The only advantage I see to the NexImage is that it was designed with the hardware to fit into the 1.25″ focuser. Windows users may have trouble with the driver crashing; I certainly did.

Here’s an idea: maybe the Live cam board will fit inside the NexImage case, then I could use the camera that works in a case that fits the focuser. I’ll have to give that a try.

new sights and old favorites – 19 April, 2009

Location: at home in Tomball, TX
Cloud cover: none
Transparency: above average (4/5)
Seeing: average (3/5)
Darkness: no moon, city glow
Wind: none
Humidity: 50%-75%
Temperature: low 60’s
Start Time: 8:20 pm CDT
End Time: 10:30 pm CDT
OTA: 8″ SC

Saturn alternately fuzzy & clear; Iapetus “close” to planet, Titan and Rhea distinct, Dione & Tethys occasionally lost in glare and turbulence.

M35 OC was amazing, brought Amanda outside to see. Many, many stars (guide info said 70+) over a narrow magnitude range within 1/2 degree region.

38 Gem DBL, could not see color difference. Guessed delta mag between 3 and 4; SNP lists them as 4.7 and 7.8.

β Mon TRIPLE, split with 12.5mm Plossl, appeared DBL in 25mm.

NGC 2392 (eskimo nebula) appeared as a fuzzy disk with a distinct central star. No detail visible.

ζ Can DBL/QUAD (tegmen); ζ1 and ζ2 easily split, close binaries beyond ability of 8″ SCT.

ι Can DBL; blue and yellow easy split. estimated yellow about 1.5 mag brighter than blue. SNP actually lists them as 4.0 and 6.6, so more like 2.6…

NGC 3242 PNEB, also called “Ghost of Jupiter”. Appeared as a fuzzy disk with no detail and no central star. Seems smaller than Jupiter (in arcsec).

Saturn again and 54 leonis – 5 April 2009

location: Tomball, TX
time: 800pm-930pm
cloud cover: 0%, gradually increasing
transparency: 100%
seeing: poor (2/5)
darkness: city sky glow, just past quarter moon
wind: gusty 10mph+
temperature: low 60’s
humitidy: 35%
dewpoint: 31F

barely able to discern tiny black gap between rings and planet. Titan, Dione, and Tethys formed a nearly equilateral triangle to the left of the rings. Rhea about 2 ring diameters to the right.

54 leonis, double star. I guessed difference of 1 mag, SNP lists them as 4.3 and 6.3. primary appeared white with blueish fringe, secondary subtle light blue. close pair but definitely not a hard split.

Saturn Rings Edge On – 2 April 2009

location: Tomball, TX
time: 730pm-900pm
cloud cover: 0%
transparency: 100%
seeing: average (3/5)
darkness: city sky glow, 1st quarter moon
wind: 5-10mph

lunar terminator crossed montes apenninus, mountain peaks were outstanding. high contrast thin fissures in SE mare vaporum: rima hyginus and rima ariadaeus. long parallel hills near rima hyginus seem un-crater-like, perhaps formed by tectonic activity?

rings of Saturn appeared as a line segment through the planet’s disc. Rhea and Dione out to the left of the rings. Tethys beyond the right edge of the rings, sometimes swallowed by bad seeing. Titan bright about 4x ring diameters from Saturn, Iapetus approx, 4x farther than Titan and surprisingly off the “line” of Saturn’s rings, probably due to orbital inclination.

having a second look – 3 February 2009

Location: at home in Tomball, TX
Cloud cover: none
Transparency: excellent (5/5)
Seeing: average (3/5)
Darkness: bright quarter moon
Wind: none
Humidity: 25%-30%
Temperature: 50’s
Start Time: 7:45 pm CST
End Time: 9:15pm CST
OTA: 8″ SC

Venus half-illuminated, very bright even with ND filter. Lots of atmospheric turbulence.

Luna brilliant, just over half illuminated. Mons Piton and Mons Pico cast long black triangles toward the dark side. Occasional turbulence visible. Subtle “fractal” texture visible on the surface of Mare Imbrium. Pulled ep and diagonal then projected image onto white paper to see entire moon in FOV. Did not try to locate Pleiades nearby.

M42 nice with 12.5mm, less detail visible than two weeks ago due to moonlight. Noticed Trapezium E for the first time, a very faint mag 10.3 star between A and B, just outside the trapezoid. Observed a pair of mag 7 or 8 stars near the mouth, and another mag 8 or 9 that formed a nearly equilateral triangle with the two stars near theta2 orionis.

Beta Mon very cool, primary slightly brighter than two companions. Close triple, clean separation in the new 12.5mm ep. Open angle about 140°-150°.

M50 appeared to consist of an isoceles triangle, pinched at the narrow vertex, with stars dotting the edges. A smaller triangle inscribed the larger, fainter stars everywhere.

NGC2264 appeared like the outline of a large arrow pointing “this way up”.

doubles on a cold cold night – 6 December 2008

Location: at home in Tomball, TX
Cloud cover: none
Transparency: above average (4/5)
Seeing: excellent (5/5)
Darkness: bright quarter moon
Wind: none
Humidity: 40% early up to 60% later
Temperature: mid-40’s F down to upper 30’s
Start Time: 9:00 pm CST
End Time: 1:00 am CST
OTA: 8″ SC

Started with M52 in Cassiopeia. Two curved lines of stars like hyperbolas, triangle left with brightest star in cluster, dim cluster above. Celestron X-Cel 12.5mm showed sharper image and dimmer stars than either of the Seibert Performance 15mm or 10mm ep’s. M52 not searchable by that name in Starry Night Pro or Celestia. Found alternate NGC 7654 in SNP.

Zeta Piscium was easy split in 32mm. In the 12.5mm one white the other almost blue.

Phi Piscium was easy split in 20mm. Could not visually distinguish which star was brightest (5.3 vs. 5.5)

Phi Cassiopeiae was a wide split in 20mm. Primary slightly yellow.

Clear Skies and Good Seeing – 18 October 2008

Location: my backyard
Time: 8pm – 11pm
cloud cover: none
temperature: low 60s
humidity: maybe 60% climbing to 80%
seeing: good (4/5)
transparency: excellent (5/5)
darkness: no moon, suburban light pollution
instrument: 8″ SCT

Don and Carol came, brought binoculars. We started by observing Jupiter. Polar cloud caps visible, almost convinced myself I could see the GRS. Four moons visible, Don and I remembered all names but Callisto.

Pointed out summer triangle Vega-Deneb-Altair and constellation Cygnus. Observed familiar double stars Albireo and epsilon lyrae.

Clusters next. Started with M39 OC in Cygnus: clear blue pinpoints. Then looked at M15 GC in Pegasus: fuzzy ball with several distinct stars.

Next came planetary nebulae M27 in Vulpecula and M57 in Lyra. Outline of M27 was distinct but dumbell shape difficult to discern. Carol’s eyes seemed more sensitive than Don’s or mine. Ring of M57 clear, Carol could see dim star at center. First time I remember seeing planetaries so clearly.

Moved to Andromeda M31. Again Carol could see some swirling where Don and I only saw fuzzy core.

Ice giants came last. Uranus was a nice cyan disk with a white spec, remarkable color. Neptune was small, hard to make out as a disk or any color.

Finally used binoculars to view rising Pleiades. Very nice view in 12×50. Air was still enough for me to see three or four stars with naked eye, in the past it seems like I mostly saw a collective glow.

Dew became a problem later, corrector began fogging lightly around 10:45 even with dew shield. Humidity had coated the binocular