steve conard willow oak observatory, gamber, md international occultation timing association (iota)...

Steve ConardWillow Oak Observatory, Gamber, MDInternational Occultation Timing Association (IOTA)Oct 20, 2012

Bruce, Russ, and I had originally hoped to do a thorough comparison of several video and digital interface cameras that could used for IOTA’s observations

Due to personal time limitations and weather, we didn’t accomplish what we had intended It became a much a less controlled test, with

fewer cameras, than we had originally intended

View it as a quick comparison of several common cameras as typically used in real-world conditions

Data collection was not as well controlled as I had hoped Intended to have a parallel telescope

recording the same field at the same time Did not take the time to fully learn to use

the Flea camera—resulting in only 8-bit data collected

The data have not rigorously been analyzed, and may contain errors More data is available to be analyzed when

time permits

C-14 on CGE mount Focal reducer used

to set f/number at about 4.0

In roll-off observatory Video data through

IOTA-VTI to Canon ZR-65 recorder

Flea data through Firewire to desktop PC

“Control” was a Stellacam EX (my SN 01)

Other video cameras Stellacam EX (SN 02) Watec 902 Ultimate (SN 01 and 02) PC164C-EX2

Firewire camera Flea 3 FL3-FW-03S3M-C

All arrays are ½” format except the PC164C-EX2 which is 1/3”

Used same field for each camera Eplison Lyra (“Double Double”) selected to

have easy reference, and was fairly high in the sky

Reference camera used before and after to look for changes

Tried to pick nights with good transparency and no visible clouds

Tangra used for data analysis Used auto aperture selection

Picked up to 6 stars for comparison

Weather clear, reasonable transparancy Tangra apertures left to automatic

selection Collected data with Stellacam EX 1 at 1

and 2 fields integration Collected data all other cameras

Varied gain on one Watec Used 1 and 2 fields on the second Stellacam

EX Collected data with Stellacam EX 1 at 1

and 2 fields integration Only minor difference in signal

before/after with Stellacam EX 1

Stellacam EX SN 2Stellacam EX SN 1 Before

Watec 902 Ultimate SN 1 Watec 902 Ultimate SN 2

PC164C-EX2 Stellacam EX SN 1 After

PC164C-EX2 may give the best combination of SNR and signal level Significantly better at all but the brightest

targets, where SNR may fold over (may not be the best choice for a bright asteroid over a fainter star)

It also may have other issues that weren’t investigated here

Watec 902 Ultimate and Stellacam EX’s are very similar Watec can produce almost as much signal as

the PC164C-EX2 when the gain is very high

Weather clear, reasonable transparancy Tangra apertures left to automatic selection Collected data with Stellacam EX 1 at 1 and

2 fields integration Collected data with Flea 3

Max’ed out the gain at 24 dB Maximized exposure time at a 30 Hz readout

rate Important: Flea was used in 8 bit mode

Collected data with Stellacam EX 1 at 1 and 2 fields integration

Only minor difference in signal before/after with Stellacam EX 1

Stellacam EX 2 Fields Flea 3

Stellacam has much larger signal level This may not be true with Flea at 12-bits

Roughly the same SNR for fainter targets, possible advantage to Flea for brighter ones

Weather clear, reasonable transparancy (same time as video comparison above)

Collected data with Stellacam EX 1 at 32 fields integration

Collected data Flea at 1.875 Hz, max exposure Gain at 24 dB Flea at 8 bits

Collected data with Stellacam EX 1 at 32 fields integration

Only minor difference in signal before/after with Stellacam for the fainter targets—the bright ones showed more change for some reason

Stellacam EX 2 Fields Flea 3

Stellacam has much larger signal level This may not be true with Flea at 12-bits

Roughly the same SNR for fainter targets, Stellacam showing saturation on brighter ones