A radical departure for me...

[ollypenrice]

I've always been doubtful about the practicality of ultra-fast optics and an advocate of mono over OSC.  So... I'm  having a change and participating in an OSC project at F2 with a CMOS camera!  (Wot no CCD???)  On top of that, I've always done everything manually: framing, focus, meridian flip, mosaic making, etc and the new setup is going to be entirely robotic. 

Most of this was Paul's idea. He was, pre-Covid, a regular guest here and was thinking about a remote collaboration with me. I have an unused slot in the robotic shed so we are moving a joint setup into it, initially aboard an Avalon Linear I bought from one of my other robotic clients. (Neither of my Mesus can run robotically without being converted to SiTech.) This will carry a Celestron RASA 8, due to arrive on Monday. Gorann's images with this instrument are just too good to ignore and he has been most helpful to us in our thinking. Merci monsieur! 😁 We'll be guiding with a Skywatcher mini guider and ZWO CMOS which I also bought from the same robotic client. My first CMOS camera...

I'm terrified of all this IT but Paul's in charge of all that! I'll keep you posted on our progress.

Olly

[saac]

Be good to follow your progress and thoughts on the OSC setup Olly.  I've only ever used OSC due largely to the weather here providing limiting opportunity.  It will be good to see what you make of it. 

Jim 

[tomato]

Great news Olly, Best of luck to the both of you with the project.

I knew it was only a matter of time  after you saw Gorann's RASA OSC Squid Nebula....

[kirkster501]

How is it on the Road to Damascus Olly? 😆

[tomato]

5 minutes ago, kirkster501 said:

How is it on the Road to Damascus Olly? 😆

Not too bumpy I hope, that will play havoc with the F2 RASA collimation.😉

[ollypenrice]

11 minutes ago, kirkster501 said:

How is it on the Road to Damascus Olly? 😆

The signpost says Damascus...

😁lly

[Mr Spock]

When I saw the title I thought for a second you were going into planetary imaging 

[pete_l]

41 minutes ago, ollypenrice said:

We'll be guiding ...

With such fast optics and a sensitive (and virtually noise-free) CMOS sensor, is guiding actually necessary?

[Chris]

Now this will be interesting! Can Olly be converted!? Stay tuned and find out in the next episode of the twilight zone! 😅 

[JeremyS]

You are pulling our legs, Olly. Just as well we all know what a joker you are. 🤣

[ollypenrice]

1 hour ago, pete_l said:

With such fast optics and a sensitive (and virtually noise-free) CMOS sensor, is guiding actually necessary?

I think it is. The resolution, from memory, will be about 1.8 arcsecs per pixel, so fairly fine (compared with the Tak/Atik 11000 at 3.5"PP) and sub lengths remain to be tested but people seem to be using 3 to 5 minutes.  Will an unguided Avalon deliver a PE of less than 0.9 arcseconds over that time? I very much doubt it, though you might conceivably get round stars if RA and Dec errors are of comparable amplitude. 

2 hours ago, Mr Spock said:

When I saw the title I thought for a second you were going into planetary imaging 

Planets? You mean those little round things just in front of the end of the telescope? 😁 No, they're too difficult and Damian Peach is too good at them!

Olly

 

[sloz1664]

Hi Olly, Good luck on your new joint adventure

You have mentioned the equipment you are going to use. But, with robotic operations, there is a need for a robust software management. Any pointers on what programme(s) are going to be used?

Steve

[ollypenrice]

4 hours ago, sloz1664 said:

Hi Olly, Good luck on your new joint adventure

You have mentioned the equipment you are going to use. But, with robotic operations, there is a need for a robust software management. Any pointers on what programme(s) are going to be used?

Steve

We'll happily publish our final choices once they are working and stable. We don't want to pump out bad information or guesswork ahead of experience, though.

Olly

[michael.h.f.wilkinson]

Sounds very interesting. I am thinking of getting a RASA 8 one of these days, so I will be watching this with interest.

[gorann]

Exciting news Olly! Nice to see that you went for the RASA8 option rather than 11. Should also be easier for the mount to handle. Are you going for an ASI2600MC?

I assume you will be thrilled by the results, after you solved any issues with sensor distance and minor tilt. My first RASA8 was perfectly collimated out of the box while my second one needed a bit of collimation, which was easy enough.

The very best of luck!

Göran

[ollypenrice]

11 minutes ago, gorann said:

Exciting news Olly! Nice to see that you went for the RASA8 option rather than 11. Should also be easier for the mount to handle. Are you going for an ASI2600MC?

I assume you will be thrilled by the results, after you solved any issues with sensor distance and minor tilt. My first RASA8 was perfectly collimated out of the box while my second one needed a bit of collimation, which was easy enough.

The very best of luck!

Göran

Thanks. Yes, the camera will be the 2600MC. I found that the 11 wouldn't fit in the observatory without the possibility of roof collision and we have a strict 'no collision possible' policy. If it can happen, one day it will happen! I need to go and do some homework on how to collimate and tune out tilt in case we have it. It's a relief to hear you say it's not too difficult! What have you found out about sub lengths, Goran?

Olly

[gorann]

2 hours ago, ollypenrice said:

Thanks. Yes, the camera will be the 2600MC. I found that the 11 wouldn't fit in the observatory without the possibility of roof collision and we have a strict 'no collision possible' policy. If it can happen, one day it will happen! I need to go and do some homework on how to collimate and tune out tilt in case we have it. It's a relief to hear you say it's not too difficult! What have you found out about sub lengths, Goran?

Olly

I always have the camera at gain 100 (where the magic drop in read noise occurs). For bright thing like M31 I did a mix of 30s and 120 s exposures. For IFN I have used 5 min exposures and with the dual-band filter I have used 5 to 8 min exposures. I assume you could use shorter expoures but there is a trade off with the amount of data to handle. Stacking can take a an hour or more with these hughe files. Each raw file is 53 Mb, but that becomes 313 Mb after debayer (32 bit as xisf in PI) and 153 Mb as a 16 bit tiff file. So you may find yourself happy that you did not go for a full format CMOS....

Collimation is done on a bright defocused star much like a SCT. There are three pairs (push-pull) of screws on the lens assembly. The main difference compared to a SCT is of course that you need to do it with a camera, and to reach the screws it needs to be a narrow camera, like a Lodestar. The RASA8 comes with two camera adapters, one for M42 and one for a C-mount camera, so for collimation you will use the c-mount adapter and a guide camera of the narrow type. There is some information in the manual (attached).

Göran

91073_RASA 8_Telescope_Manual_5Lang_Web Only.pdf

[ollypenrice]

2 minutes ago, gorann said:

I always have the camera at gain 100 (where the magic drop in read noise occurs). For bright thing like M31 I did a mix of 30s and 120 s exposures. For IFN I have used 5 min exposures and with the dual-band filter I have used 5 to 8 min exposures. I assume you could use shorter expoures but there is a trade off with the amount of data to handle. Stacking can take a an hour or more with these hughe files. Each raw file is 53 Mb, but that becomes 313 Mb after debayer (32 bit as xisf in PI) and 153 Mb as a 16 bit tiff file. So you may find yourself happy that you did not go for a full format CMOS....

Collimation is done on a bright defocused star much like a SCT. There are three pairs (push-pull) of screws on the lens assembly. The main difference compared to a SCT is of course that you need to do it with a camera, and to reach the screws it needs to be a narrow camera, like a Lodestar. The RASA8 comes with two camera adapters, one for M42 and one for a C-mount camera, so for collimation you will use the c-mount adapter and a guide camera of the narrow type. There is some information in the manual (attached).

Göran

91073_RASA 8_Telescope_Manual_5Lang_Web Only.pdf 537.33 kB · 0 downloads

Great information. Thanks. I guess the guide cam will do for collimation but I also have Lodestars. I rather hope it's like your first one!

Olly

[gorann]

14 minutes ago, ollypenrice said:

Great information. Thanks. I guess the guide cam will do for collimation but I also have Lodestars. I rather hope it's like your first one!

Olly

A Lodestar should be fine or any 1.25" camera. I see that the Lodestar X2 has a CS-thread while the adapter that comes with the scope has a male C-thread, so you need a C to CS adapter. I seem to remeber that I used a Lodestar X2 for my collimation and had to use a C to CS adapter ring. You may have one laying around.

[wimvb]

23 hours ago, pete_l said:

With such fast optics and a sensitive (and virtually noise-free) CMOS sensor, is guiding actually necessary?

From a dark site, you need longer exposures to clear the read noise floor. Unless you use a cmos at high gain (low dynamic range), the exposure time will be too long for guideless imaging. At low gain, expect even L to need at least 1-2 minutes exposure time. With an osc, the exposure times quoted by Olly and Göran are what you would expect.

Next thing Olly will drop down on us, is that he will do the processing entirely in PixInsight. 😋

[wimvb]

15 hours ago, ollypenrice said:

We'll happily publish our final choices once they are working and stable.

Clear give aways: INDI with Kstars/ekos

For robotic imaging, to quote George Clooney: ”what else?”

 😋😋

[ollypenrice]

17 minutes ago, wimvb said:

Clear give aways: INDI with Kstars/ekos

For robotic imaging, to quote George Clooney: ”what else?”

 😋😋

This is all new to me so I don't know these systems. Can you eloborate a bit?

Olly

[wimvb]

11 minutes ago, ollypenrice said:

This is all new to me so I don't know these systems. Can you eloborate a bit?

Olly

in short, indi is an alternative to ascom, a system of drivers and software for hardware control (mount, focuser, camera, guiding, observatory automation, input from weather station, etc). It runs mainly on linux, as opposed to ascom which runs on windows. Indi connects also to a user interface or stellarium program. Many users let a stellarium program called kstars connect to indi. These programs that are the user interface to the hardware are called clients. Even PixInsight has some basic functionality to be used as a client. Ekos is the plugin to kstars that does the actual hardware controll.

https://indilib.org/
One of many videos on youtube:

finally:

 

[ollypenrice]

Scope arrived tod

[ollypenrice]

Scope arrived today, seemingly in good health and in a dent-free box delivered by UPS who are always, and by far, the best around here.

I had a to-do when fitting the top dovetail because the longer screws in the bag didn't fit in the scope. Too big. But... it turns out the accessory holes in the front of the tube are fractionally bigger than those in the rear of the tube so they need fractionally different bolts. Well why not? Why miss out on a chance to add confusion? 

The three-column pier raiser in Avalon Sexy Red will have to go because, in the Polaris position, the roof already touches the top of the rig, even without camera. I may have room for a lower height-raiser once we see the front loaded with camera and dewshield. We want it as high as possible because we can and do keep shooting down to the horizon on some targets, here, but the observatory wall will cut us off.

Now we need a camera, a PC and the usual pasta-fest of cables...

Olly