Site Tests of Astronomical Seeing
Cabrillo College
Observatory is located at the end of "Well Road", along Porter Gulch
Creek at the extreme northwest corner of campus.Coordinates:
10" pier: Lat=36 59 33.95, Long=-121 55 26.49, elev 211 ft (WGS84 on google
Earth).
Well Rd is the inconspicuous one-lane dirt road leading into the eucalyptus
grove, off Soquel Drive immediately east of Porter Gulch Road and next to the
western entrance to the upper campus, shown on the photograph at right. At right
is the Google-Earth view of the Cabrillo Campus with the observatory and entrance
road intersection with Soquel Drive labelled.
While this site is astronomically not as good as our previous location on the hilltop above campus, it has the advantage of no line-of-sight to any lights whatsoever, and is isolated from the rest of the campus. It has good western and northern horizons, 15-20 degree southern horizons, and 20-23 degree eastern horizons. Our enclosures were moved in the summer of 2003. The observatory is surrounded by oak and chaparral hillsides on two sides, and Porter Gulch Creek on the other. The observatory consists of two buildings - a 640 sqft storage building, and the dome building.
The
Dome Building
The 350 sqft dome building houses our 12" Meade LX200 telescope on a Losmandy G11 mount with Gemini navigation system. It has a 6' fiberglass HomeDome from Technical Innovations installed on the roof, and an 8' concrete pier with a 4'x4'x4' foundation supporting the telescope. The scope is housed in a 16'x8' room which is thermally isolated from the "warm room". The warm room has a desk facing the telescope through a window with 2 computer stations - "Spock" controls the SBIG ST2000xcm CCD camera while "Sulu" navigates the telescope. Each are WinXP machines. The computers are networked together and connected to the internet via a 80211b wireless connection. The dome is controlled by motors interfaced with infrared sensors which automatically keep the telescope and dome in synch.We have an ST2000XCM 2.1 megapixel color CCD camera with 2-stage thermoelectric cooling for dedicated imaging at this telescope.
Between the two buildings is our photometry station. On observing nights, we carry out a 3'x5' table stop and mount it on permanent cinder block supports. Then bring out a weather-shelter enclosure box which contains a computer system. And finally, our 10" Meade LX200 Schmidt-Cass is carried out and placed on a steel adapter bolted to a concrete pier. Two-star alignment and computerized 'go to' ability make finding these faint variable stars straightforward. An underground conduit carries datalines from the telescope + Optec SSP3A photometer to the computer. 2-person student teams rotate through this station on observing nights and typically take data on new variables or on eclipsing binary stars. Single channel photometry is done with the Optec SSP3A photometer connected to a computer. Data acquistion and data reduction is accomplished with the RPHOT photometry software package, which I wrote back in the early '90's and license to Optec for distribution to many individuals, colleges and research institutions around the world. Here is a .pdf version of a paper on the RPHOT package. (you must have the free Adobe Acrobat reader installed when you click).
We have access to the new Cabrillo College photolab and dark rooms. Our Astro
9A/B/C astrophotography students can choose from a growing array of equipment.
Our new SBIG
ST2000XCM color CCD camera is mounted on the 12" LX200 dome
scope for color imaging. We recently acquired an SBIG ST4000xcm
CCD camera with a single-shot color 2048x2048 detector. We also have
an SBIG ST7xe camera to be used for CCD photometry mainly. In 2005, we 
acquired
a Meade DSI
and also a Meade DSI
Pro and LPI imagers. Also a Nikon D40 which can be coupled to the
eyepiece and a Canon ZR45mc camcorder for taking planet and lunar photos suitable
for stacking and processing. In the geology/astronomy lab room 705 we have 7
computers for student photo processing, and a Dimage Elite II film and negative
scanner. Best of all, we have two Losmandy GM8 mounts for autoguided astrophotography.
They're beautifully machined and work like a champ. Astrophotography
classes are generally taught in the Fall only. Telescopes suitable
for guided astrophotography include the 12" LX200 under the dome, the 8"
LX200GPS, 8" f/4 Meade LXD75 Schmidt-Newtonian and 80mm Megrez APO flourite
refractor.
Two other concrete piers are available for mounting our other telescopes. During observing nights, most students are engaged in projects with portable instruments. These include...
-17" f/5 home-made Dobsonian
-13" f/5 Odyssey Dobsonian
-12.5" f/5 "Star Splitter" Dobsonian
- Three 8" Meade SCT's
- 8" Odyssey Dobsonian
- two 6" Newtonians
- 6 pair of 7x50 binoculars
- 2 pair 10x70 binoculars usually mounted on tripod
- Megrez II 80mm Flourite APO refractor
- two Meade 8" f/4 Schmidt Newtonians
- an LXD75 mount generally used for wide-angle tracking of cameras mounted to a dovetail adapter piece
- Kiwi video time inserter for occultation work
- Meade 8" f/10 LX200gps, DSI Pro, and MaxIm DL/CCD software
- 4 computers and a laptop in the Dome Building, all packed with imaging software including Photoshop, CCDOPS, and Registax v. 4
In
Winter '03/04 we built a redwood deck and grassy knoll northwest of the main
pad. This gives us a lower horizon towards the east and northeast - our darkest
direction. Astronomy clubber Jeff Jolin donated a nice campground-sized picnic
table on the knoll above the deck. The deck is fitted with surrounding seating
suitable for a whole Astro 8 or Astro 9 class by thrifty use of available materials.
It also serves as a BBQ spot for star parties.
Our old steel shipping containers were rusting away, leaking, and too small. Chuck Mornard and the CEM Department's construction engineering class of Spring '05 did a fantastic job of hammering together a fine building. Thank you, Chuck! (The building is in the background of the GM8 picture above right.). In Spring '07 I proposed a replacement for the main observatory dome shed with a similar building to be constructed by CEM once again. It got high ranking in the division spending proposals and was constructed during winter '07/'08. Having the computers and people in a separate room eliminates the problem of warm air rising right through the open dome slit and across the optical path. This will improve the notoriously poor seeing we have experienced. It'll also be more comfortable and spacious for the astronomers. Here's a photo page on the the whole process... The new observatory building has 4 computers for student use in case it gets cloudy partway through the evening, and space for many more to curl up with their laptops and work on their digital astrophotos.