Laurin Dave

Very nice Miguel, great detail and colour. looks like you are using ASI1600.. which is calibrated best using matched darks /flatdarks rather than bias, especially that from an different camera.. also best to take the camera off the scope to take your darks to make sure there are no light leaks. It'll be even better Dave

Hi Tomato What problem are you trying to solve? Are your slave subs bad when the master scope focuses? if so I'd suspect your polar alignment or maybe the RA rate on the Mesu is slightly out … my system is Esprit 150 SX46 with piggybacked Esprit 100 ASI1600.. I run an OAG on the Esprit 150.. when that focusses I lose guiding.... but the Mesu is so good (4" peak to peak over about 30 minutes) that over 120 seconds you just don't notice on the Esprit 100 subs (with your longer focal length you may need to use 60seconds) .. I dither and lose those but its maybe 10% of the frames at most.. last night I reduced the dither scale and lost only 10 out of 200 ! I know this isn't the answer to your question but based on my experience I think you'd make you're life much simpler by investing in an ASI1600mm (same size sensor as a 683) or similar and running colour on that at 60 or 120sec exposure and put one of your 683 chip cameras with an OAG on the other scope and run luminance though it at 10 or 20 minutes .. You'll also get back that lovely fov and at 1" pp you won't lose any real resolution .. you could also bin the ASI1600 2x2 .. and scope alignment will be less demanding.. with the ASI1600 bright stars can be a bit messy.. Why not experiment by replacing one of your 178s with a 683/OAG as the master and running short binned subs on the 178. And what a week of imaging … 7 out of the last 8 nights clear all night.. its been like being at your place Olly Dave

Thanks Dave.. I really must have a go at a Comet... just no idea how to. Dave

Another one from the exceptional clear skies we are having.. The Black Eye Galaxy Messier 64 is a relatively isolated spiral galaxy located 17 million light years away in Coma Berenices and has a diameter of about 54,000 light-years. It was discovered by Edward Pigott in March 1779, and independently by Johann Elert Bode in April of the same year, as well as by Charles Messier in 1780. A dark band of absorbing dust in front of the galaxy's bright nucleus gave rise to its nicknames of the "Black Eye" or "Evil Eye" galaxy. 8 hours Lum on Esprit150/SX46 and 2.7hrs each RGB on Esprit100/ASI1600 mostly captured whilst I was fast asleep. Processed in Pixinsight (Drizzle Integrated) and Photoshop. Thanks for looking Dave

Thanks, I guess the galaxy is distorted giving it a 3-D look.. like an unwinding Danish Pastry .. the wide field is about 80% crop of full frame.. 1000 mm focal length and APS-H chip

Very nice... I do believe though that your dark subtraction is not working properly as you can see the 183 chips characteristic starburst amp glow on the right. Are you using matched darks? and if so have you got "optimise" turned off in Pixinsight's calibration process? Sorting that out would remove the starburst.

Galaxy season in Berkshire has certainly benefited form the amazing clear skies lately. This one's from Tuesday night, its M94 in Canes Venatici.. 15 million light years away, the inner ring is about 30000 light years across and the faint halo (actually dim spiral arms) about 100000lyr. 8hrs Lum though Esprit150/SX46 and 2,5hrs each RGB Esprit100/ASI1600. Processed in APP, Pixinsight and Photoshop. Thanks for looking and stay safe Dave

Sounds excellent Gav.. we're doing our Astro Society meeting on Zoom tonight.. and ps... the dome sync now behaves perfectly!

Thank you Goran.. and yes I love my Esprits.. Dave

Thanks Gav.. I didn't do any Ha as none of the amateur images of it I looked at showed any .. It's lovely , I got a few hours on it Monday night and just had to go back for more. I'm just loving these clear skies... two more forecast here which will mean 6 in a row .. plus last Friday. Presume its much the same down your way. As you say stay safe.. Dave

NGC 4725 is an intermediate barred spiral galaxy in the constellation Coma Berenices with a prominent ring structure and seemingly only one arm…. It is over 100 thousand light-years across and lies 41 million light-years away. It is a Seyfert Galaxy, suggesting an active galactic nucleus containing a supermassive black hole. I saw this in Ruben Kier's 100 Best Astrophotography Targets. Started on Monday night and finished last night, 12hrs Lum through Espri150/SX46 and 4 hours each RGB through piggybacked Esprit100/ASI1600. Processed in APP, Pixinsight and Photoshop. I've included close up and wide field views. Thanks for looking Dave

Very nice, certainly looks Much better in LRGB than my attempt in HOO. Good framing too Dave

are you calibrating with matched darks? ( which you need to with this camera) And what exposures are you using .. following advice I read on CN ie use between 0.1 and 2 seconds and put a delay in between subs of 10 seconds.. never fails, I target similar ADU

Clever... I could do with a Tomatobro

Imaged last night from Berkshire through my Esprit150/SX46 (6hrs lum) and Esprit100/ASI1600 (2hrs each RGB). processed in APP, Pixinsight and Photoshop. NGC 4565 is an edge-on spiral galaxy about 30 to 50 million light-years away in the constellation Coma Berenices, it is estimated to be140000 light years in diameter and contain a trillion stars. It lies close to the North Galactic Pole and has a visual magnitude of approximately 10. It is known as the Needle Galaxy for its narrow profile. It was first recorded by William Herschel in 1785. Also in the frame are NGC 4562 a barred spiral galaxy (also known as NGC4565a) and elliptical galaxy NGC4555 plus many smaller and more distant galaxies. NGC 4555 is a solitary elliptical galaxy about 125,000 light-years across, and about 310 million light years distant. Observations by the Chandra X-ray Observatory have shown it to be surrounded by a halo of hot gas about 400000 light years across. The hot gas has a temperature of around 10,000,000 deg C. The galaxy is one of the few elliptical galaxies proven to have significant amounts of dark matter. Large amounts of dark matter are necessary to prevent the gas from escaping the galaxy; the visible mass clearly is not large enough to hold such an extensive gas halo. The dark matter halo is estimated to have 10 times the mass of the stars in the galaxy. NGC 4555 is also important because of its isolation. Most elliptical galaxies are found in the cores of groups and clusters of galaxies, and almost all those for which dark matter estimates are available are located in the centres of these larger systems. In these circumstances it impossible to know whether the dark matter is associated with the galaxy or the surrounding cluster. NGC 4555, as a field galaxy is not part of any group or cluster, and therefore provides strong evidence that dark matter can be associated with individual ellipticals. Despite being isolated, NGC 4555 is part of the Coma Supercluster. (Source Wiki) Thanks for looking Dave

Pleased you got it fixed 🙂

I'd try tightening everything up to start with and see if you can move anything however slightly by hand.. also check both focusers as these are also a source of flexure and adjust if necessary Dave

Well done.. all journeys start with the first step!

Looks like its differential flexure between the rigs.. that the shorter exposure have less elongation somewhat confirms this. How beefy is the dual saddle/alignment ? (just re-read your thread and its quite beefy - I'd check its all as tight as it can be) @tomato had a thread on this issue with his dual Esprit150 not that long ago.. worth a search for Dave

Very nice Goran.. and impressive detail.. not far from M106 if I remember correctly .. Dave

All good ideas Many years ago on my LX50 I used the rubber bit from a garden watering can rose with a plastic lid from a jar of peanut butter over the top..

I don’t use bias so not sure about that.. I think the difference is that in APP you have to tick a box to turn on optimisation whereas in PI you have to untick it to turn it off.. you want it off so with APP the default is correct.. it’s all quite tricky remembering what to do so I always calibrate and integrate my flats and darks (I don’t calibrate darks) separately in PI to make sure they’re ok and use masters in APP and Pi.. in PI there’s a file format conversion script in the “Scripts” menu "Batch Processing" "Batch Format Conversion" if you need to convert .xisf files to .fits.. also note that the image integration parameters you need for flats in PI are not the default ones.. (you need to use multiplicative scaling , equalise fluxes etc) whereas APP knows it’s integrating flats hth Dave

I’d keep it “simple” to start within and use the same exposures for RG and B .. I use 120 seconds for them and 60s for lum with my ASI1600 all at Unity gain and -10 deg C.. most importantly with this camera ( if you didn’t already know) is to use matched darks and flat darks to calibrate your lights and flats and not to use dark optimisation in the calibration routine .. using the same exposures means you can build a darks library and keep using it for months.. best way to take darks is to take the camera off the scope put its cap on and point it face down onto a desk. This avoids issues with any potential light leaks.. for my flats I have a dark library in steps of 0.1 secs from 0.1 to 1.5 secs and use whatever is closest. Dave

You need to have the “optimise” setting turned off for Darks in PI calibration routine.. otherwise it messes things up.. assume you are using matched darks and flat darks and no bias ... I nearly always calibrate in PI, integrate and colour combine in APP then move back to PI (sometimes use APP for background extraction) for a bit of stretching (ArcSinh, Histogram and Curves) then Photoshop for the rest.

Goran.... It'll be the dark lines emanating from his eyes .. a sure sign he's been in too much sun