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HomeNewsAstronomy and SpaceTPoint modelling – Astronomy Now

TPoint modelling – Astronomy Now


Figure 1: When organising a pointing mannequin in TPoint, you may select the variety of stars used through the Fewer Targets/More Targets slider proven on the backside of the menu. The decrease altitude restrict of the celebs used could be set by clicking on the crammed orange circle proven at centre-left and dragging it to extend or lower the circle dimension. In this manner, stars under a sure altitude are excluded. All photos: Nik Szymanek.

At a look

Minimum system necessities

macOS: 2GHz Intel Core Duo or sooner, macOS Sierra (10.12), High Sierra (10.13), Mojave (10.14) or Catalina (10.15) 512MB RAM, 64MB video RAM, 2.5GB disk space

Windows: 1.5GHz or sooner, Intel Pentium 4, Pentium M, Pentium D or higher, or AMD Ok-8 (Athlon) or higher, Windows 10, 512MB RAM, 128MB video RAM, 2.5GB disk space

Linux: A pc working 64-bit x86 Linux Ubuntu 12.04 LTS or later, Ubuntu GUI and OpenGL, 512MB RAM, 2GB minimal disc space

Raspberry Pi: Third-generation Raspberry Pi system (Raspberry Pi 3 Model B or later) SanDisk Ultra PLUS 16GB microSDHC UHS-1 card, 2GB minimal free space, Well-ventilated venture case (fan not crucial) Optional exterior 9-pin serial port

Price: $595

Details: bisque.com

Back within the July 2018 difficulty of Astronomy Now, I reviewed The Sky X Professional software program with an emphasis on deep-sky imaging. The Sky planetarium bundle has been out there for a few years, and every version has included many new and thrilling options. For instance, more moderen variations launched the flexibility to manage imaging units through a ‘Camera Add-on’, which might be bought individually. Another addition was TPoint, which is equatorial-mount-modelling software program, legendary for its functionality to enhance telescope pointing and used on a number of skilled telescopes.

My 2018 assessment centered on the capabilities and ease-of-use of the Camera Add-on, since I’d already used TPoint, my being a long-time fan of The Sky X. After a number of nights in my back-garden observatory, I used to be extraordinarily impressed with the efficiency and capabilities of the bundle. It actually appears to make sense to manage every thing from throughout the identical software program. A latest commercial in Astronomy Now alerted me to a brand new launch of the bundle, now named The Sky Imaging Edition (TSIE), and Software Bisque, the US firm that provides the software program, kindly allowed me to obtain the complete imaging bundle for this assessment. It appears that the reasoning behind this new launch is that the Camera Add-on and TPoint are actually included within the worth, and the brand new model works out barely cheaper. At the time of writing the software program prices roughly £465 ($100 for the primary 12 months’s subscription, plus a $495 one-time sign-up payment). While this isn’t insignificant, it’s really excellent worth for cash since it is a very complete imaging and planetarium bundle.

Installation was seamless and allowed the retention of user-definable options from earlier variations, akin to field-of-view indicators, in addition to the panoramic view of my again backyard that I’d used beforehand to personalise my observing location. The planetarium show seems to be nice, is simple to make use of and could be very customisable. Overall, this system is just about the identical to have a look at as the sooner model, however I did spot some new options, which I’ll come to later. Since the sooner assessment, I’d carried out an improve from Windows 7 to Windows 10 and, throughout that process The Sky X had misplaced the flexibility to see my imaging digital camera. This wasn’t a showstopper as I used to be in a position to make use of the software program’s personal ASCOM driver to manage the digital camera. Happily, after the improve the digital camera was accessible once more utilizing the native QSI drivers.

Set-up

During a welcome run of three consecutive clear and regular nights in mid-September I used to be in a position to check out the brand new bundle for deep-sky CCD imaging. I’d just lately bought a ‘previously enjoyed’ QSI 683wsg CCD digital camera, and it was this that I used for the assessment, fairly than my outdated stalwart QSI 583wsg digital camera. During the daytime I used to be in a position to rapidly configure the opposite observatory gear. My imaging mount for the previous ten years has been a Paramount ME together with a GSO 254mm (10-inch) Ritchey–Chrétien telescope fitted with an Astro-Physics 0.7× focal reducer, giving a focal size of 1,440mm. The QSI 683 digital camera has an inner eight-position filter-wheel, loaded with LRGB and narrowband filters, which is managed through the digital camera driver. I additionally used a trusty Starlight Xpress Lodestar auto-guiding digital camera connected to the QSI 683’s integral off-axis guider port. The sensitivity of the information digital camera permits the acquisition of an acceptable information star whenever. I’m additionally utilizing a Moonlite two-inch digital focuser that’s operated through a Lakeside controller. This was arrange utilizing the ASCOM protocol in The Sky Imaging Edition software program. Happily, every thing related flawlessly, which was an incredible aid.

Figure 2: An picture could be plate-solved by clicking on ‘Photo > To Image Link’ within the FITS Viewer display.

First night time

My plan was to spend the primary night time creating a brand new pointing mannequin for the telescope. Although I’ve used TPoint for a few years, I’ve by no means been in a position to get a very good mannequin that I used to be glad with. Of course, if something is bodily modified within the imaging system, even by a small quantity, then the mannequin is degraded. The set up of the brand new digital camera and rebalancing of the mount would have executed this, so it was positively time for a brand new mannequin. The methodology behind TPoint could be very advanced however the user-interface is comparatively easy. There are two methods of constructing a pointing mannequin. The guide methodology requires that the telescope be pointed to a star and a picture taken. The star will almost definitely be offset from the sensor’s centre place by some small quantity, relying on the standard of the equatorial mount used. The star could be centred utilizing the mount’s hand-controller or through software program centring (I at all times have a set of crosshairs on the display to assist align the star). When centred, the ‘Add Pointing Sample’ button is pressed. This is repeated many instances with the telescope pointing at a big collection of stars, unfold evenly throughout the sky and both facet of the meridian to construct up a report of all of the potential mechanical and mount-pointing errors within the system. Alternatively, and significantly better, is to make use of the ‘Automated Pointing Calibration Run’ strategy. A certain quantity of knowledge needs to be supplied, akin to publicity time (I used three seconds), the picture scale in arcseconds per pixel, binning, and so forth. Next, you select what number of stars to make use of for the automated run, utilizing the menu proven in Figure 1. The slider on the backside of the display is dragged to the left for fewer stars for use within the mannequin, and to the best for extra stars. The space of sky used for modelling stars could be adjusted utilizing the orange button proven at centre-left, which expands or contracts the blue circle, permitting stars near the horizon to be excluded. After doing all this I ended up with a pointing run of 62 stars, which might be the decrease finish of a super mannequin, however it was start line. There are 4 tick packing containers proven on the decrease left. ‘Randomize’ creates, unsurprisingly, a random however well-spaced set of stars and is advisable within the consumer guide. I clicked on ‘Sort for Dome’ as I assumed this could create a logical path for the celebs throughout the sky, making motion of the dome aperture much less frequent, however this didn’t appear to be the case. I’d deliberate to include a five-second delay between star photos to permit extra time to maneuver the dome, however in my pleasure I forgot, so I ended up scrambling round attempting to maintain up with the slewing telescope.

Figure 3: You can set TPoint present the trail that the telescope will take when working the pointing mannequin (proven right here in yellow). The blue traces are constellation markers.

Plate-solving issues

Proceeding to the subsequent tab, ‘Acquire Pointing Samples’ shows a vertical record of the chosen stars. Clicking on the ‘Run’ button begins the process. The telescope slewed to the primary star, took a picture, tried to ‘plate-solve’ however then failed. Plate-solving is the place the celebs in a picture are plotted after which matched with a big database of stars from a list. Once profitable, the mount’s place is understood with nice accuracy. Unfortunately, after the primary failure the mount slewed to the subsequent star and in addition failed. This was a supply of confusion because the ‘FITS Viewer’ window (extra on this window later) permits the celebs within the picture to be plate-solved by the observer utilizing the ‘To Image Link’ choice from the drop-list, proven in Figure 2. Image Link is what The Sky calls plate-solving. When I attempted this, it labored completely. I revisited the sooner setup menus and after a little bit of head-scratching unticked the ‘Use All Sky Image Link for automated pointing runs’ field and fortunately every thing labored nice after that. I subsequently found that there’s an ‘All Sky Database’ file out there for obtain from the Software Bisque web site that may be put in within the ‘Astrometry’ folder of TSIE and which can repair the difficulty. Over the subsequent 45 minutes or so the mount continued to slew across the sky and purchased 61 pointing samples. The lone failure was due to my not being quick sufficient with the dome. The frenetic path of the telescope across the sky is proven in Figure 3, with the crammed yellow dots marking the positions of the celebs used for the modelling run.

Figure 4: Once the supermodel has been created, TPoint creates a scatter plot displaying the brand new pointing accuracy. This graphic reveals the vast majority of stars contained inside a 36-arcsecond circle. From this level on, the mount’s positional accuracy improved remarkably and it might be even higher with a bigger pointing mannequin.

When the pointing run is accomplished the outcomes are amalgamated right into a ‘supermodel’ that improves the pointing additional. Figure 4 reveals the outcomes after the supermodel was utilized. The interior circle of the scatter plot at prime left measures 36.3 arcseconds and incorporates the vast majority of the 61 pointing samples. TPoint may also give a exact polar-alignment evaluation primarily based on the mannequin. Clicking on the ‘Polar Alignment’ tab reveals the end result. It appears that my azimuthal adjustment is barely out however the altitude adjustment is excellent. TPoint states how a lot the mount needs to be adjusted and through which path, however one other mannequin could be required, so I left it alone (Figure 5).

Figure 5: TPoint divulges polar-alignment errors revealed by the pointing mannequin, and reveals the best way to alter the mount to right them.

Amazing accuracy

By this level I used to be fairly eager to see how effectively the telescope was pointing, so I slewed it onto M27, the Dumbbell Nebula in Vulpecula. The left-hand pane of Figure 6 reveals the position of M27 after the primary slew. This is a extremely magnified view of the central space of the CCD sensor and you may see the central star of the planetary nebula simply to the decrease left of the crosshair’s centre level. This actually represents nice pointing accuracy and I’d really feel no have to place this any higher earlier than beginning an imaging run. The full sensor is proven within the small picture at lower-middle.

Figure 6: The left pane reveals an odd slew onto M27, the Dumbbell Nebula, with the central star positioned barely under left of centre. The proper pane reveals the position of M27 after a full meridian flip, which is even higher, with the central star nearer to the centre of the crosshairs.

I revisited M27 later, after it had crossed the meridian, in order that the mount needed to perform a full meridian flip, rotating via 360 levels to strategy the goal from the alternative facet of the sky. When the picture downloaded I used to be amazed on the positional accuracy. The central star is proven simply fractionally under the crosshair’s centre level on this flipped picture (right-hand pane of Figure 6).

Figure 7: TSIE’s ‘Find’ then ‘Slew’ instructions has positioned the star very near the centre of the crosshairs (left). For higher positioning, the ‘Closed Loop Slew’ choice plate-solves the primary picture after which adjusts the mount by the requisite quantity to put the star or one other object proper on the centre of the crosshairs (proper).

There are a few factors value mentioning right here. Figure 7 reveals the intense star Caph (beta Cassiopeia) that I’d used as a pointing take a look at after the TPoint run. It’s displayed in TSIE’s ‘FITS Viewer’ display. Once a picture has been taken and downloaded, it’s mechanically opened on this viewer. A purple crosshair could be turned on utilizing the tick-box on the prime proper. After the preliminary slew, the star was positioned nearly on the crosshair, once more representing nice pointing accuracy. This could be refined much more through the use of a function referred to as ‘Closed Loop Slew’, which isn’t new to the most recent version however is certainly value utilizing. Here’s the way it works. A star or deep-sky object is chosen utilizing the ‘Find’ tab on the left of the primary display. Once discovered, plenty of info is displayed, together with right ascension, declination, rise time, transit time, and so forth. Next, click on on ‘Closed Loop Slew’ and the mount will slew to the goal, take a picture after which Image Link it (plate-solve). Once executed, the mount is shifted to centre the goal after which one other picture is taken. When the picture is downloaded, the goal ought to be smack bang on the centre of the picture (see right-hand pane of Figure 7). You may also select how the picture is displayed. The ‘Show Histogram’ button at top-left, subsequent to the ‘Photo’ tab, opens the image-scaling choices throughout the underside of the menu and at bottom-right is a drop-list containing a number of choices. The first is ‘SBIG’, and anybody who has owned a Santa Barbara Instruments Group CCD digital camera might be accustomed to its show properties. Two sliders, labelled ‘Scale’ and ‘Highlights’, and a histogram are proven and these could be manipulated to present good shadows and brightness values, significantly necessary if you’re manually specializing in a star. A brand new choice within the record caught my eye, intriguingly named ‘Heuristic’. Clicking on this adjustments the show fairly dramatically and offers a view that resembles one obtained with Digital Development Processing, logarithmic scaling or the ‘auto stretch’ function in PixInsight. I additionally used it when checking the autofocus capabilities (extra of which within the subsequent difficulty) as a result of it confirmed stellar diffraction spikes very clearly. Figure 8 reveals a monochrome 10-minute publicity of M27 utilizing the SBIG choice on the left and Heuristic on the best.

Figure 8: A brand new function to TSIE is the ‘Heuristic’ show within the FITS Viewer window. This gives a compressed, logarithmic-type scaling that resembles PixInsight’s ‘auto stretch’ show.

It was a unbelievable first night time. In the subsequent difficulty we’ll chronicle how the software program carried out throughout the second night time, and specifically assess the autofocus and auto-guiding capabilities of The Sky Imaging Edition.

Nik Szymanek is an astro-imager primarily based in Essex and is the creator of Shooting Stars andShooting Stars II, whichare Astronomy Now books about fashionable astrophotography methods.





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