Category: Astro knowledge
Astro knowledge / Focuser / Optics
Re: visual astronomy
It’s so cute when I use my a highly-tuned astrograph with an eyepiece of all things. Actually, I’m just lazy. Because I haven’t really figured out the whole motor focuser thing, I […]
modded DSLR IR response
The February 2009 issue of S&T, pp. 81, has a side-by-side photographic example and explanation of the UV/IR cut filter in DSLRs. The UV/IR cut filter that comes with the camera is […]
Whence C9.25?
I decided to upgrade the C-8 to a C9.25. As a photographer, I need different lenses to do different work. The 8” is awesome down to ~10′, but below that, it’s pretty […]
Starfield memorization: M51
In an image of M51 taken near Feb 5, 2009 (todo: find this image), there is a really pretty blue star that’s very nearby the galaxy. I’d like to use that star […]
Re: success! M51 full calibration
Art Morton wrote: > The silly little galaxies are quite visible too. (: I hardly ever see shots of M51 with the little guys showing. Also, I *never* see shots with that […]
Astro knowledge / General / Long Exposure Photography / Observing Reports
Re: So, what is skyglow? Must need a dark site
Art Morton wrote: > awesome photo not shot by me > > The way you get dark sky in the Bay Area is to get to the top of a local foothill […]
Re: drawtube requirements
Art Morton wrote: > On Jan 28, 2009, at 9:38 AM, Jimbo S. Harris wrote: >> Do you know if the focus shifts “in” or “out” during the course of >> the […]
Astro knowledge / ATM / Optics
big, fast, light
16” f/5 honeycomb mirror for $1500 According to the website, these optics are ~20% lighter than solid mirrors of comparable thickness. So this one might weigh only 20# instead of 26#. That […]
Re: causality, light cones, and speed limits
OK, two votes for “We are all officially living in The Matrix”. When Arnold was elected governator, that was Jon Stewart’s comment. J Anthony James wrote: > You may need to lay […]
causality, light cones, and speed limits
I have a problem with causality being hampered by the speed of light. Just because I didn’t see something happen before its effect takes place doesn’t mean that it’s not possible. Why […]
RECENT UPDATE
Polar Alignment Calculations
Here’s a page that derives Polar Alignment Calculations. (update 5/2020: the original site is gone, so I found the text on Wayback and am inserting it below. This is by the original […]
Gear / Observatory / Telescope
Special Guest Star takes the mount at Hilltop O
The Astro Jedi needed somewhere to store his light sab—- I mean, bucket, and I was only too happy to accommodate him. I have decided that I need to come to a […]
General / Maintenance / Observatory
Dome shutter is motorized again!
I finally decided to bite the bullet and fix the shutter motor. Things went sideways last winter, and I’ve been opening the shutter manually (and tying it shut with rope, so we […]
Trixie 2017 – tube mods
I finally got around to cutting the MTA-UTA tubes to length; the only eyepiece that would come to focus with the focuser spacer in place is the Televue 55mm Plossl. If I […]
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Observatory
Observatory 2.0 – Time has come today!
General / Maintenance
First Light, a deeper look
Mount / Observatory / Telescope
Observatory 2.0 – Result!
Observatory
Observatory 2.0 – The Pier goes in
Gear / General / Maintenance
Martin Farmer Wormblock installation notes
Deep Sky / Long Exposure Photography
NGC2244, The Rosette Nebula
Deep Sky / Long Exposure Photography
Another beautiful night.