SBIG DSS-7 sensitivity

[George]

I am interested in learning if the SBIG DSS-7 can handle the strong light intensity from direct sunlight reflected off of a white object, or will this risk damage to the sensor? I want to use this spectrometer for obtaining spectral irradiance data of reflected sunlight.

[andyschlei]

George,

I have an ST-10 and I need both a 70% neutral density filter and an Ha filter to image the Moon at a few tenths of a second. I would imagine that it would be very hard not to overwhelm the CCD with the shortest exposure possible of reflected sunlight, but that is just my guess.

Have you tried asking SBIG?

--Andy

[George]

Have you tried asking SBIG?

Yes, and I had a quick response. Unfortunately, my question to them concerned the risk of damaging the sensor. This thought is related to the fact the Hubble can not get within about 50 deg., IIRC, of the sun and is normally kept from getting too close to the moon's direction also.

I should have asked about the shutter speed issues instead. I will ask and will report back here.

[George]

Apparently, multiple filters will be required to measure reflected sunlight, though just how much attenuation is still unclear. The change in spectral irradiance as a result of the use of filters is easily determined by comparing a calibration light with and without the filters.

[jonathancassidy]

The observatory i work for has an SBIG 8E CCD. They use ACE software for pointing control. I am asking if anyone can tell me if and how the CCD can do guiding on chip.

http://www.rpi.edu/dept/phys/observatory/
Jonathan Cassidy, public observing manager
jcassidy@prudentialmanor.com
518.423.3510

[jonathancassidy]

Hello,

I am Jonathan Cassidy, public observing manager for the Hirsch Observatory, my night job:

http://www.rpi.edu/dept/phys/observatory/

We host lab work for 3 colleges and 600 - 1,000 public visitors each year for observing. We are opening a night of imaging. Our system is very stable and capable of doing fine imaging and spectroscopy work. We need help with this.

I have a question about auto guiding using an SBIG 8E CCD and ACE software. I am looking to find out how the two can work together to give us exacting guiding.

Jonathan Cassidy, associate broker, Prudential Manor Homes, REALTORS, My day job
jcassidy@prudentialmanor.com
518.423.3510

[andyschlei]

Hello,

I am Jonathan Cassidy, public observing manager for the Hirsch Observatory, my night job:

http://www.rpi.edu/dept/phys/observatory/

We host lab work for 3 colleges and 600 - 1,000 public visitors each year for observing. We are opening a night of imaging. Our system is very stable and capable of doing fine imaging and spectroscopy work. We need help with this.

I have a question about auto guiding using an SBIG 8E CCD and ACE software. I am looking to find out how the two can work together to give us exacting guiding.

Jonathan Cassidy, associate broker, Prudential Manor Homes, REALTORS, My day job
jcassidy@prudentialmanor.com
518.423.3510

Welcome to the board!

I've never heard of ACE and a google search only turned up ACE: Astronomical Cataloging Environment.

SBIG gives away CCDOPS, and it works both to capture images and perform autoguiding using the on-board guide chip. Other alternatives are MaximDL and CCDSoft among others.

HTH,

--Andy

P.S., Perhaps this deserves its own thread?

[George]

All I could find was a user's manual. Have you tried contacting the ACE or SBIG folks?

[RickJ]

Yes, and I had a quick response. Unfortunately, my question to them concerned the risk of damaging the sensor. This thought is related to the fact the Hubble can not get within about 50 deg., IIRC, of the sun and is normally kept from getting too close to the moon's direction also.

I should have asked about the shutter speed issues instead. I will ask and will report back here.

It's total hogwash that Hubble can't image the moon. It can and has!
http://hubblesite.org/newscenter/arc...leases/1999/14

It also can look at the Earth which is far brighter -- and does. Though not to look in your windows. It uses the rapid movement of the earth to create its flats. Pretty hard to put a light box on Hubble so they use the earth instead. Or so a scientist friend who has Hubble experience calibrating Hubble images tells me.

Obviously the DSS-7 won't be hurt by reflected light, nothing in it is at all light sensitive though direct sunlight could cook cemented lenses that I believe are in it so that is to be avoided.

You don't say what camera you are using it on. In any case your sensor won't be hurt by bright reflected light, say from a white building lit by bright sunlight. But it may be over exposed. This depends on the efficiency of the grating and the amount of dispersion it gives. I'd expect light levels are likely low enough not to be a problem. Not having ever used one I can't say for sure and the camera used will have some say in this as well. They very greatly in shutter speed depending on model. If it is you'll need neutral density filter to get the light down to a level that doesn't overwhelm the chip. You'll also need to know how "neutral" your filter is or it will skew the spectrum you are trying to measure.

Another consideration could be the shutter. Some SBIG cameras have no mechanical shutter so bright unfocused light sometimes gets through the darkened optical window shutter to hit the sensor. This can screw up the spectrum of a bright object that has been not fully blocked by the optical shutter. Optical shutters aren't 100% light blocking. Also with such cameras you will also need to block bright light when taking darks with such cameras. My ST-7 is very bad in this regard. With the mechanical shutter on my ST-11000 this isn't a problem but a real fast shutter when taking flats can create an uneven exposure that screws them up. I find I need a light level that results in an exposure of a couple seconds to prevent this.

But bright reflected light can't harm the sensor, direct solar light can, due to the heat cooking the chip rather than the super bright light itself.

Rick

[George]

It's total hogwash that Hubble can't image the moon. It can and has!
http://hubblesite.org/newscenter/arc...leases/1999/14

Please note what I said. The Moon and Earth can be imaged, but not "normally" because damage is possible.

See the ESA answer to question no. 2 of the FAQ.

http://www.spacetelescope.org/about/faq.html

You don't say what camera you are using it on. In any case your sensor won't be hurt by bright reflected light, say from a white building lit by bright sunlight. But it may be over exposed. This depends on the efficiency of the grating and the amount of dispersion it gives. I'd expect light levels are likely low enough not to be a problem. Not having ever used one I can't say for sure and the camera used will have some say in this as well. They very greatly in shutter speed depending on model. If it is you'll need neutral density filter to get the light down to a level that doesn't overwhelm the chip. You'll also need to know how "neutral" your filter is or it will skew the spectrum you are trying to measure.

Thanks.

[jonathancassidy]

Andy, thank you for the lead as to the software from SBIG. I have sent that on to the president of the student club. We have a 16" RD scope on a very heavy mount in a dome. We have done decent pics. We need to auto guide to get to the great pics level.