I can't get a break!

[Larry 1969]

Good day all!
Some of you know I've been having some difficulties getting decent images lately and last night was no exception...
I set up and picked a target (NGC 7822) and got my plan running at 8:30 PM (Just after astronomical darkness).
I watched the first 30 or so subs come in and they looked pretty good so I went to bed. My target was to hit the meridian at 12:22 AM.
I woke up at 3:00 AM and went out to my laptop to make sure the automated meridian flip executed properly and it did.
It was at that time that I noticed some type of halo around the bright stars. I thought maybe it was haze again so I left the plan run.
I got up again at 5:30 AM and the frames were a bit lighter (probably due to the moon) and I stopped the plan there. I had about 170 images.
I opened all light frames in DSS and registered them with a 6% star detection threshold.
DSS applies a "score" to each frame for some type of reference I suppose but I noticed quite a few frames with a very low score.
I noticed a significant drop in score after the meridian flip. That's also when the halos began to appear. (Coincidence)?
I went through each frame and deleted satellites and any frames with poor shaped stars. I made two stacked images.
One with a score limit set to 500 (which was all frames before the flip) and one with all frames.
The first image is approx 3 hours while the second is approx 7 hours. Both processed almost identically.

I also processed a single frame from early in the session:

And a single frame from the end with the halos (making it almost impossible to process)

Any thoughts? I'm REALLY hoping it's not an equipment problem...
Thanks!

Larry

[STEVE333]

Hi Larry - Is it possible there is some problem with dew forming on the objective lens of the telescope and/or on the window of the camera? That would certainly explain what you are seeing.

Just as an aside I keep a 1-Gallon ziplock plastic bag pulled over and around my camera whenever it is not being used. Inside the plastic bag I have a desiccant package to dry out the air. This helps to prevent any dew from forming on the inside of the camera window when it is cooled down for use. This idea of keeping the camera in a "desiccated environment" when not in use was suggested by several other users of cooled cameras. So far it is working for me.

Steve

[Mac]

Looks like the effects of dew. Are you using dew heaters, if not, invest in some. I couldn't image without them here in Ohio.

[Larry 1969]

Hi Larry - Is it possible there is some problem with dew forming on the objective lens of the telescope and/or on the window of the camera? That would certainly explain what you are seeing.

Just as an aside I keep a 1-Gallon ziplock plastic bag pulled over and around my camera whenever it is not being used. Inside the plastic bag I have a desiccant package to dry out the air. This helps to prevent any dew from forming on the inside of the camera window when it is cooled down for use. This idea of keeping the camera in a "desiccated environment" when not in use was suggested by several other users of cooled cameras. So far it is working for me.

Steve

I've looked into the scope with a flashlight and saw no evidence of dew...
It's a Newtonian so I thought dew wasn't much of an issue...
Maybe a shield in my near future though..

Larry

[sdbodin]

Well, with my Dob, the insidious dew would form on the secondary, not really visible unless you look down the eyepiece drawtube.

Steve

[Larry 1969]

Well, with my Dob, the insidious dew would form on the secondary, not really visible unless you look down the eyepiece drawtube.

Steve

I suppose that makes sense. Looking at my pictures again, I suppose it does look like dew...
I didn't even suspect the secondary because it appears almost upside down. I wouldn't think dew would be able to "settle" on it...

Looks like a shield is in order.

Thanks!

Larry

[Larry 1969]

Just as an aside I keep a 1-Gallon ziplock plastic bag pulled over and around my camera whenever it is not being used. Inside the plastic bag I have a desiccant package to dry out the air. This helps to prevent any dew from forming on the inside of the camera window when it is cooled down for use. This idea of keeping the camera in a "desiccated environment" when not in use was suggested by several other users of cooled cameras. So far it is working for me.

Steve

I meant to comment on this portion of your reply as well.
I leave the camera in the scope (trying to avoid taking calibration frames every session).
I did have a problem once after leaving everything set up through the next day (trying to avoid having to PA the next night).
It sat out in the sun and it was pretty hot. I noticed the bottom half of my images were distorted but gradually cleared up.
I figured it was moisture on the sensor window so I recharged the desiccant per the instructions and that solved my issue.
I have an ASI071 MC Pro that has a dew heater built in.
Do you leave the camera in the scope and somehow attach the ziplock bag?

Thanks!

Larry

[bobharmony]

Dew can be an issue with Newts. Most often it will form on the secondary or the camera sensor. In really humid conditions you may find it on the primary as well.

I try to take my flats while still set up for the night. When it is dewy (I usually see it on the laptop or the lens caps, which I leave inside facing down at all times) I will try to leave the camera in place on the scope until I can take replacement flats after things dry out. It doesn't always work, but a sessions data has been saved once or twice by doing this.

Bob

[STEVE333]

I leave the camera in the scope (trying to avoid taking calibration frames every session).
I did have a problem once after leaving everything set up through the next day (trying to avoid having to PA the next night).
It sat out in the sun and it was pretty hot. I noticed the bottom half of my images were distorted but gradually cleared up.
I figured it was moisture on the sensor window so I recharged the desiccant per the instructions and that solved my issue.
I have an ASI071 MC Pro that has a dew heater built in.
Do you leave the camera in the scope and somehow attach the ziplock bag?

Thanks!

Larry

Hi Larry - I leave my camera attached for the same reasons. When I put the telescope away I pull a Gallon ziplock bag over the camera/filter-wheel combination. The dessicant pack is inside the ziplock bag. Then I pull the ziplock bag "zipper" up until it squeezes down around the "neck" connecting the filter wheel assembly to the telescope. Because my telescope is a refractor it is sealed, so, no moisture enters through the telescope. Thus, the desiccant keeps the filter wheel and camera dry. If the inside of your telescope is open this approach may not work for you.

Hopefully some of the suggestions here will help resolve your problems.

Cheers - Steve