MarkS

This is really a work in progress. It is the RGB only of an object that needs Narrow Band, particularly OIII. However, the weather has been uncooperative, and other matters also got in the way, so I'm now having to wait a few weeks. In the meantime, this image is 3 hours only of RGB, shot with an Officina Stellare 130 Hiper refractor (to get the 3 x 2.3 degree fov), G3-16200, and DDM 60 unguided; all subs 5 min. A synthetic L channel was made from all subs to generate a final LRGB image. But it needs OIII to delineate the blues better. I've marked the position of the Vela pulsar, which is the remains of the original cause of the shockwaves.

Hi Tommy, Really fine image which repays zooming in on! Mark

Amenophis, y I don't know about step size, but the AAF3 has a precision encoder, and the position is read out to 1 micron. During a run with my ASA10N, focus position is generally maintained to within +/-1 or 2 microns. Hope this helps. Mark

Many thanks Antonio, Mark

Another fine image, Antonio! Mark

Yes, very nice, Antonio. A bit far North for me here, but not all that far from the image I just posted, also in Monoceros... Mark

Mike, I haven't had that happen to me, but I have had occasion to stop Sequence during a run. It was possible to re-establish things by simply turning off Sequence and TheSkyX, return the scope to Zenith park position, turn on TSX and connect telescope, and sync on a star high near the meridian. Then turn on Sequence and connect and sync and run. This can be done pretty fast..... For a disaster like yours, I guess you now know what to do!!: Leave the DDM and camera power supplies on; turn off all software; Shut down the PC - force it if necessary; re-boot the PC; turn on the system as usual; sync TSX and Sequence on the target and run Sequence...... If you're quick, the sensor is unlikely to be shocked - especially in UK temperatures. I suspect that the PC lock-up you experienced may be a matter of the particular set up sequence of your system rather than a fundamental problem with any of the software. Hopefully, someone else can offer you more assistance than this! Mark

This remarkably coloured star forming region lies in Monoceros about 2700 ly away. The bluish reflection nebula just above the orange patch is VdB69. Other designated objects are VdB67, VdB68, VdB72 and LBN999. The surrounds are very dusty. RGB 6hrs total exposure time, ASA10N, G3-16200, DDM85A. FOV approx 90' X 70'. Mark

There is a lot of literature on the subject of Newtonian collimation. There is very little on initial alignment of the secondary mirror, and even less on emphasizing its critical importance to performance of fast astrographs with large camera sensors. Whilst axial collimation alone may be fine for observing and perhaps for very small photographic fields of view, it is a necessary BUT INSUFFICIENT condition for, say, an ASA10N and 16200 or 16803 class camera. Such systems have very low tolerance to errors of co-planarity between the telescope focal plane and the camera sensor plane. Exact co-planarity is achieved only when three conditions are met: 1. The primary mirror optical axis must be at exactly 90 degrees to the focuser optical axis; 2. The primary and focuser optical axes must intersect on the secondary mirror optical centre; 3. The elliptical secondary mirror major axis must be at exactly 45 degrees to both the primary and focuser axes. Using any of the axial collimation tools, 'perfect' axial collimation can be achieved without ANY of these conditions being met. The critical starting point is condition 2. This is effectively about the position of the secondary mirror along the primary axis. If this condition is not met, the telescope plane of focus will not be the same as the camera sensor plane, no matter how good the axial collimation is. Yet I have seen articles which tell me that the secondary initial alignment is not too critical! On the other hand, ASA documentation gives the secondary offset figure for the telescope, but it doesn't really stress why it is so critical to get it right. The best way to get it right that I have found is to block the primary reflection with a card, and using the Cat's Eye adjust the secondary so that its projected circular edge in the view is EXACTLY concentric with the edge of the CAT's Eye in the focuser barrel. Then I collimate the system as usual, and recheck the concentricity at the end of that process. The only final check on how perfect it all is, is to take a set of images of populous star fields and check the corners (I use Pixinsight's Aberration Inspector script.) How critical is it? According to a rough calculation for an ASA10N and a 16200 camera, a 0.6 mm error in the primary mirror to secondary mirror distance will cause the focal plane to be non-aligned with the sensor plane by ~ 35 micron across the sensor diagonal. This will 'eat up' the total depth of focus at F/3.6 of +/- 17 micron. Without trying too hard I have achieved beautiful axial collimation using Jim Fly XLK and Cat's Eye for secondary distances differing by 2 mm. All this becomes a matter for attention if for any reason secondary mirror removal is required, or if the central secondary mounting bolt has been moved. Hopefully, this is 'too much information' for everyone, but it may help any desperados who can't get round stars across their images even when the collimation is good! Season's greetings all! Mark

Hi Antonio, Yet another masterpiece! Technically awesome and beautifully rendered. Mark

Many thanks, Antonio Mark

This interesting target has the added bonus of several distant galaxies. Shot over 2 nights, total exposure of 5 hours 20 min RGB only. SQL 21.5 but seeing was fairly poor at ~4". ASA10N at f/3.6; DDM85A; Moravian G3-16200; Astrodon Filters. FOV 50' X 40'

Many thanks Antonio. Mark

Spectacular image, Antonio! But the exposure time is huge!!!!! For interest, what would the result look like with, say, 9 hours total? Mark

Very nice image, Thomas. (The G3-16200 is a fine camera) Mark

Hi Waldemar, The USB3 signal wires are definitely heavier and better constructed than USB2, but the USB2 signal wires within the standard USB3 cable are thinner and there is only one pair, whereas the USB3 wires are paired. On Type A connectors, the USB3 do not connect to the USB2 contacts. Whether the USB2 wires are better quality in USB3 cables than they are in USB2 cables I do not know.... I have certainly had no problems using USB3 cables from mount to computer. Mark

Looking at the cable specs for USB3, it is clear that a USB3 cable Type A connects to a USB2 Type A socket via a separate pair of wires from the USB3 ones. That is, Ian is right - it is probably better to spend your money on best quality USB2 cables than USB3 ones. Mark

Thomas and Luis, Many thanks. I appreciate your encouragement. Mark

Hi Antonio, Interesting find! Lovely detail and colour - your trademark! Mark

Hi Luis, Great image - detail and colour look superb. Nice to see this, as Andromeda is very low on my horizon.... Mark

Hi Robert, This may not be very helpful, but after a recent extremely baffling problem with a new camera, I am prompted to ask if you have tried changing the USB cable? They are notoriously unreliable. Regarding your query about start-up sequence, I have always started the mount before turning on the computer and Autoslew. When I was learning the ASA system, I found that this sequence always worked, and I've never varied it. I'd like to know if others do the same? Mark

A hazy and cirrus-strewn sky forced me to target a Globular Cluster, as this was, I thought, the best chance of a result. M55 has very low metallicity - it's very old, even for a GC - but it also has an unusual number of 'blue stragglers', apparently the result of relatively recent star mergers and collisions. In the event, I got about 3.5 hours RGB - all 2.5 minute subs to minimise star saturation. Half of the blue subs were unfortunately very heavily contaminated with scatter through cloud, so some clean-up was necessary. Otherwise there is only a little decon to sharpen things a bit, background neutralisation, and photometric colour calibration in Pixinsight, followed by a simple histogram stretch. ASA10N at f/3.6; DDM85A; G3-16200; Astrodon filter set. Field of view 32' x 25'.

Thomas, Great set of images. If I had to choose one it would be M100. Mark

Hi Antonio, Another splendid image of a dark nebula! Mark

When you install Pinpoint you must also install a star catalog - GSC is generally recommended. You can download it from dc3-dreams website. GSC sits on the PC hard disc, and the route to it must be entered into Sequence > Settings > Plate Solve > Set path. In my case the path is simply C:\GSC11. Hope this helps Mark