August 5, 2010
The recent bout of cloudiness allowed me to spend some time upgrading my camera systems. With the recent bout of clear nights, I’m happy to announce 2 new cameras.
My previous systems (SALSA1 and 2) have been based on PC164C low-light cameras and Computar 4mm f/1.2 lenses. The latest addition is called SALSA3 and is a Watec 902H2 Ultimate. This type of camera and other closely related ones are the primary choice of most video meteor observers. I originally went with the PC164Cs because of their cheaper cost. That’s great and all but the Watec’s are much more sensitive resulting in greater numbers of detected meteors.
The plan was also to upgrade to a faster or just larger aperture lens by either using a Computar 6mm f/1.4 or 3.8mm f/0.8 lens. Unfortunately both lenses have been discontinued so until one pops up on eBay I’ll be using the old 4mm f/1.2. The big downside to this lens is it was made for a 1/3″ chip (like the PC164C) and not a 1/2″ chip (like the Watec) so the field is heavily vignetted at the edges (meaning the lens does not properly illuminate the entire field of the Watec).
The 2nd new camera has actually been up and running for a few months now. This near all-sky camera is part of the Sentinel system developed by Sandia Labs and New Mexico State University. The original system has been modified with a Computar 2.3mm f/1.4 lens. The larger lens means a smaller field of view (~120° across) but allows fainter stars to be detected for the purpose of astrometry. Sirko Molau, the author of the MetRec suite of meteor detection software that I use, modified his astrometry calibration software to work with such a large field. As a result, I can now report accurate positions and shower affiliations for this camera. Thank you, Sirko!
Up till now, my meteor detections were flagged as TUS (for Tucson) in the table below. From here on out I will differentiate between the near all-sky camera and the narrow FOV camera (ALLS for the near all-sky and SAL3 for SALSA3). SALSA3 can detect meteors down to magnitude 2-3 while the all-sky can only see down to magnitude 0-1. Since most showers are dominated by larger meteors, a larger fraction of the all-sky camera’s detected meteors should be shower members. The last 2 nights confirm this as all but 4 of the 39 meteors detected by the all-sky camera were shower members (90% shower members). In comparison 34 of 88 SALSA3 meteors were not shower members (61% shower members).
The Perseids (PER) are already producing good numbers. Visual observations to the IMO are reporting up to 20 per hour from dark sites. The Southern Delta Aquariids (SDA) are also going strong at about half the Perseid strength. Surprisingly the minor Beta Perseid (BPE) shower also produced good numbers last night. [Editor’s note: I misidentified this shower as the Beta Pegasids yesterday. It is actually the Beta Perseids.]
The weather forecast shows a return of monsoon activity starting tonight. Luckily the long-range forecast calls for another round of clearing by the middle of next week, just in time for the Perseid maximum.
Obs Date(UT) Time TOT SPO ANT CAP PAU PER SDA AUP BPE ERI SAL3 2010-08-05 06h47m 47 21 3 2 1 9 4 1 4 2 ALLS 2010-08-05 07h49m 21 3 0 0 1 10 5 0 2 0 SAL3 2010-08-04 08h25m 41 13 2 3 2 10 9 0 1 1 ALLS 2010-08-04 07h07m 18 1 0 0 0 11 4 0 1 1 SAL3 2010-08-03 06h35m 28 9 1 0 3 6 9 0 - - SAL3 - SALSA3 camera in Tucson (Carl Hergenrother) ALLS - Near all-sky camera in Tucson (Carl Hergenrother) SDG - Camera in San Diego operated by Bob Lunsford TotTime - Total amount of time each camera looked for meteors TOT - Total number of meteors detected SPO - Sporadics (meteors not affiliated with any particular meteor shower) ANT - Antihelion CAP - Alpha Capricornids PAU - Piscis Austrinids PER - Perseids SDA - Southern Delta Aquariids AUP - August Piscids BPE - Beta Perseids ERI - Eta Eridanids