tomato

If you have PHD open during the calibration, it will give you information about the process in the bottom left hand corner. It should take about 10-30 steps and you can see the star being brought back to the centre when it moves in the opposite direction. Given the problem you had I would definitely recommend you do a calibration at the start of the session, if it successfully calibrates that rules out any initial set up problems.

No worries, I’m too far North for the delights of the Galactic centre, and galaxy imagers have the ‘dreaded moon’ to contend with every month. But like I say, there is something up there for everyone.

I have just added up my images captured since August 2020, 15 in total and that includes a 24 hr mosaic project, but obviously having a dual rig helps. If you want to intensify your image capture I thoroughly recommend a “fast” scope like the RASA and one of the latest sensitive CMOS OSC cameras. Just look at @gorann’s results from a dark location to see what can be achieved with integration hourly totals still in single figures, and at the other extreme, reasonable results can be obtained on some NB objects when the moon is out in about an hour. ‘Dreaded galaxy season’? My favourite time of the year mate! Plenty of choice up there for all tastes.👍

Quite an imposing title for the talk, sounds more in keeping with PI. I’ll be there.

Here is 7.2 hours on NGC 4051, an intermediate spiral galaxy in Ursa Major, discovered by Sir John Herschel in 1788. It is around 45 million light years distant and (it says here) has a super massive black hole at it's centre of 1.73 million solar masses. The image is rather spoilt by a large hair on the Lum camera sensor which created a big shadow to the top right of the galaxy, which I think caused the diffraction spikes on the star in this region, based on the observation that the spikes disappeared if I moved the star out of this region. The hair has now been removed, after spoiling another image. I was too lazy in assuming the flats would take care of it, lesson learned, I will be more vigilant on sensor cleanliness in future. Details Dual Esprit 150/ASI 178 cameras binned 2x2. L 73 x 3 mins R 24 x 3 mins G 25 x 3 mins B 22 x 3 mins Calibrated and stacked in APP, processed in APP, AP and Gimp. Thanks for looking

Great start! I have about 4 hrs of LRGB data on this target, it is coming out a silvery blue on the initial stack but after doing a star colour calibration in APP the galaxy has indeed acquired a golden hue. It certainly has an intriguing appearance, the dust lanes look almost artificial, too 'clean'. Unfortunately I had a substantial dust doughnut on the Lum camera which I thought would calibrate out but flats do have a limit to what they can clean up so I think I need to take the lum data again.

I have a Velcro wrap around the camera to help secure the lead but it is a bit iffy. But could a loose usb plug create a low signal scenario from the camera?

I have a OAG with an ASI 120 mini guide cam running PHD2 with synchronised guiding using NINA. The other night the SNR value went from 270+ to 14 in about a second, PHD reported star mass change and the guide image looked like cloud had come over. However the scopes were pointing through the aperture and the sky was clear. I stopped guiding, disconnected and reconnected the camera and all was OK. Last night it did the same thing again about 10 mins apart but fine after that. Note the camera is not losing connection, so it is not a dodgy USB lead, it is as if the signal being detected is being massively reduced. The only other thing I noted was it happened just before or after a dither operation. Any thoughts?

Yes, great detail for 30 mins of data. Sky transparency was great last night, when there were no clouds in the way.

Absolutely stunning images, I confess I prefer the stars to be present in images, but you have done a superb job in seamlessly removing them.👍

My understanding is that the read noise on CMOS sensors is not as repeatable on very short exposures when compared to CCDs hence the use of flat darks rather than bias frames with CMOS cameras. However, I confess I’ve never tried bias frames with CMOS cameras so can’t comment on the difference from first hand experience, and the latest generation of CMOS cameras have very little read noise anyway.

Welcome to SGL, I think you have a well thought out approach to imaging, it is tempting to go for the high end stuff before maximising what you can do with your existing kit, the former is the route I took, but fortunately I do now have the time (if not the clear nights) to try and get my skill level to catch up. +1 for the Star Adventurer, the ability to image relatively easily from a dark site can really boost the quality of the images captured and thereby maintain your enthusiasm for this hobby. Clear Skies

Got 90 mins of half decent subs despite a bit of a gale blowing, one advantage of a dome, especially if your target is on the leeward side.

I have access to two 150s, one purchased new in 2018 with the ES Reid inspection, the other second hand (but as new) in 2019 without the inspection. To my untrained eye they look Ok even at sub zero temperatures, the scopes are housed in an unheated observatory, not sure if this is a factor. Hope your replacement performs, I could only dream of a dual APO rig of this aperture without these SW scopes.

A very classy whirlpool, not many unguided images can take a crop like this.👍

A wonderful image, you have done a great job with the PI mosaic scripts. Don't worry about pixel peeping, this is panorama to be enjoyed at full scale.

Thanks, I forgot to mention that I am binning the sensors 2x2, so I am imaging at 0.94 arcsec/pixel.

Thanks Martin, the background is a little messy due to a humungous dust bunny on the Lum camera. It was clearly evident on the flats but was not fully calibrated out by APP for some reason. I am finally beginning to realise that data is king, I thought my large aperture dual rig could cut some corners, but on these kind of targets I need to be in double figures on the integration hours.

+1 for a powered shutter and detector for rain protection, especially in the UK. If I am in the adjacent warm room and here rain on my tin roof I can get out and close the shutter quick enough, but not if I have retired to the living room and monitoring via TeamViewer or something similar. Also I have seen perfectly good subs being collected and rain lashing in through the open aperture, such are the vagaries of the British Weather.

Here is my effort, using the V2 Ha data. Processed in StarTools V1.7 first making a LRGB composite, then blending in the Ha using Ivo's tutorial, except I used the Distance option in the Layers module, rather than Lighten. Final adjustments in APP, mainly using the HSL tool to try and accentuate the dust lane details. The data is, as with previous sets, absolutely first class, I was hoping LRGB would be more straightforward than NB, but there is so much depth and detail, I don't know where to start and when to stop. The Ha data is amazing, so much going on at this wavelength in M33.

I connect PHD, calibrate etc, before connecting to NINA, I have a few issues with NINA, but PHD isn’t one of them. Re taking flats, I thought you could set the target %ADU, exposure time etc, with the sliders in the Flats Wizard? I suppose if the software cannot satisfy all of the target criteria, it is perhaps working to a hierarchy, hence that is why it won’t meet your set %ADU?

This is just over 8 hrs of data on NGC 3184, the Little Pinwheel Galaxy in Ursa Major, captured over the previous two nights with the dual Esprit 150/ASI 178 set up. The subs were superior on the first night but 4 hrs was not enough data, adding the inferior data from last night has improved the final result. Again, a host of more distant galaxies are present in the image, I have run it through PI Imagesolver and annotation scripts, but most are not identified. L 80 x 3 mins RGB 26 x 3 mins each channel. Calibrated and stacked in APP, processed in APP and AP. Thanks for looking.

Agreed, trying to guide through NB filters is not a good idea, you wont be detecting many stars through these filters on a 3 second exposure.

Hi, welcome to SGL. I would agree that the OAG should be in front of the filter wheel (ie closer to to the stars than the filters), filter aperture and sensor size are usually quite tight so you need your filters as close to the sensor as you can get to avoid serious vignetting.

I presume your FW and camera are in a screwed together arrangement on the focuser and so therefore must be reasonably centralised in the optical train? If so, is there perhaps some tilt/misalignment with your flats illumination source?