Mysterious disappearing spots

[RJN]

The Siding Spring (SD) CONCAM now frequently shows dark spots that suddenly appear and disappear. The dark spots are there for several frames and do NOT rotate with the sky. Then they are gone. Here are two consecutive frames from SD:

and 4 minutes later


Note the dark spot just below Sirius in the first frame is gone in the second frame. This is only one example. I have seen many spots like this come and go over the past week at SD.

What are these spots?

I have my own rather strange theory but I am curious if anyone else would like to make a guess.

- RJN

[Andre Phillips]

> http://nightskylive.net/asterisk/viewtopic.php?t=193

Hi Robert,

I'll take a long shot guess that somewhere on the CONCAM enclosure a family of spiders has taken up residence. The tiny dots are from wayward tiny child spiders who are exploring the local terrain, including inside the rain dome. I'll have an investigation today and report.

Cheers,

Andre

[RJN]

Hi Andre!

Well since you're actually minding the Siding Spring CONCAM you would know best. I was guessing that they were ladybugs. Once I was out at the Kitt Peak site during the day and noticed a ladybug purched right at the top of the lens. It seemed that the ladybug considered the bowed fisheye lens as a sort of "mother ladybug".

You are likely right since spiders have been seen at Siding Spring before:
http://nightskylive.net/asterisk/viewtopic.php?t=3
although previously they are noticably larger.

At least its not a bird!
http://antwrp.gsfc.nasa.gov/apod/ap030401.html
I understand the talons of that owl scratched the lens.

I am curious to know what you find out!

- RJN

[Andre Phillips]

Hi Robert,

Last night I again noticed the moving black spots on nightskylive.net/sd images, which prompted me this afternoon to remove the large family of tiny spiders which have recently taken up residence on-and-around the concam enclosure. Some of the more enterprising spiders had found their way underneath the weather dome, and during the night they moved backwards and forwards on tiny silk threads suspended inside the dome. During the day they retreated from the dome to a more shady spot.

So, I've removed and hosed-out the aluminium sunshield, and polished the lens and dome, and the black spots will very likely not be present on nightskylive.net/sd images for a few months to come. But I expect they'll be back sometime. As I think you well appreciate, one can never underestimate the ability of tiny bugs to find their way into bug-proof enclosures...

Cheers,

Andre