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Posts Made By: Doug Scobel

August 9, 2004 12:40 PM Forum: Solar System Observing

Sunspots 08-Aug-2004

Posted By Doug Scobel
Did some sunspot observing Sunday, around 12:30 EDT. There's a very nice, large, and complex group on the following limb, along with some faculae. There's also a smaller pair on the preceding limb. The seeing was very steady and some really fine structure was visible. Here are a couple images (although they looked much better visually). They were through my 8-inch f/8 Newtonian, Nikon Coolpix 800 mounted to a 14mm TeleVue Radian eyepiece.

Doug

August 9, 2004 04:50 PM Forum: Telescope Making

Re: Cooler than ambient?

Posted By Doug Scobel
Dan, I'm no expert but my understanding is that it radiates its heat to the open sky, which has a much lower effective temperature. The only way dew can form on an object when the air is warmer than the dew point is for that object to cool below ambient.

Others who are more knowledgeable than me can elaborate.

Best regards,
Doug

September 15, 2004 12:18 PM Forum: Solar System Observing

Pluto observation from BFSP - Sep 11-12 2004

Posted By Doug Scobel
I wanted to share my Pluto observation from the Black Forest Star Party this past weekend. Even after 35 years of observing, I guess there are still new things to see! grin

The field was a challenge to sketch, as there were many more really faint stars than those that I recorded (I was able to see 16th mag stars at the zenith in my 13"). And Pluto, at 14th magnitude, didn't really stand out, so I had to wait for the second night to see which one moved. The faintest stars I sketched are around mag 15.

Also observed Neptune's moon Triton, and the two brightest moons of Uranus Oberon and Titania, all firsts for me also. (BTW, Uranus was naked eye, NELM was 6.4 at the zenith).

Enjoy,
Doug

September 20, 2004 04:42 PM Forum: Deep Sky Observing

Re: Blinking Planetary

Posted By Doug Scobel
The technical explanation is that it's just being coy.

Doug

September 28, 2004 04:49 PM Forum: Telescope Making

Jumping in late: Re:.....what mirror coating?

Posted By Doug Scobel
Mike,

Sorry to jump in late also.

I have enhanced coatings on both mirrors of my 13.1" dob. I don't see any scatter attributable to the coatings, but figure-wise the primary is average, so it's hard to tell. I had the primary coated by Precision Applied Products, about ten years ago, and the secondary is a Lumicon 2.6". Both are coated with enhanced aluminum.

I was seeing stars down to 16th magnitude at the Black Forest Star Party under mag 6.4 skies a few weeks ago. Theoretically, I should only be able to go down to around 15.5.

Many folks who look through my scope comment on how contrasty the images are, and I can't disagree.

If enhanced caotings are problematic, then you can't prove it by me.

Anecdotal, yes, but hope this helps anyway.

Regards,
Doug

October 18, 2004 02:45 PM Forum: Telescope Making

Basement too cool for Gugolz 64?

Posted By Doug Scobel
Sorry for the redundancy, but I received no replies from this same question on the Making and Testing Optics forum (which is very new and maybe not a lot of folks know that it's there).

I'm about to start work on figuring a 6-inch f/4.5 Pyrex mirror (it's already polished out). My basement stays around 63-65 degrees F, at around 60-70% relative humidity. I plan on using Gugolz 64 pitch. Does this sound OK? Or should I work upstairs where it's warmer (say, 70-72 degrees) but less humid?

The reason I ask is at f/4.5 I'll need a fairly compliant lap, and I'm wondering if a too-cool environment will make it too hard.

Thanks,
Doug

October 28, 2004 12:00 PM Forum: Solar System Observing

Lunar eclipse from Michigan

Posted By Doug Scobel
Well, here in Ann Arbor we were blessed with better sky conditions than anticipated and we had a great view of the eclipse from my back yard. I was surprised at how dark the moon got - quite ruddy colored. In the 13" quite a few stars were visible around the moon during totality. Did anyone else see that star get occulted? I would guess it was around 11th or 12th magnitude. It was there one moment, and then blink it was gone. One could really visualize the moon's motion in its orbit as it overtook the star.

Because this is the last total lunar eclipse until 2007, I thought I'd try to get a few shots. As usual, I used my Nikon Coolpix 800, hand-held to a 28mm Pretoria eyepiece in my 13" f/4.5 dob. Exposures were one full second, so not too sharp since the camera was hand-held. This shot is right after the start of totality. Two more pics after this one, mid-eclipse and just before end of totality.

Enjoy,
Doug

November 8, 2004 03:07 PM Forum: Solar System Observing

Sunspots 7-Nov-2004

Posted By Doug Scobel
Observed and imaged the major sunspots now visible on the sun's face. Group AR 696 is incredibly detailed, and is visible naked-eye (with filtration, of course). Groups AR 693 and 698 on the western limb are impressive also. I took this image Sunday afternoon around 14:50 EST. I used my usual setup, 8-inch f/8 (7-inch f/9 with Baader solar filter) Newtonian reflector, Nikon Coolpix 800 mounted to Televue 14mm Radian eyepiece. Post processed and color added in Paint Shop Pro. North is near the top.

AR 696 is the large sunspot group near the center of the solar disk, while on the western limb, AR 698 is the northern spot, and the group to the south is group AR 693. I'm not sure about the spot right on the limb. It might be AR 685.

Enjoy,
Doug

January 4, 2005 10:09 PM Forum: Film Astrophotography - Imaging and Processing

Best film for Comet Machholz?

Posted By Doug Scobel
Any recommendations re: the best color print film to use for Comet Machholz? If it ever clears here in SE Michigan I hope to take some shots of it using an OM-1, with 200mm f/4 lens.

Thanks,
Doug

January 17, 2005 10:22 PM Forum: Solar System Observing

Finally! C/2004 Q2 Machholz!

Posted By Doug Scobel
The clouds finally parted and I got a chance to observe Comet Machholz Sunday evening (16-Jan-2005) from my driveway. With the light pollution and almost first quarter moon, the sky wasn't real dark so I couldn't make out a tail. Still, it was a pretty sight in a nice field. Here's my observation report and sketch. (Let me know if you can't read the text and I'll transcribe it.)

Enjoy,
Doug

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