Omega with a Flip

This session involved using the new test rig which comprises a Stella Mira 66 ED APO refractor with a field flattener and Altair magnetic 2" filter holder with an Altair Quadband filter; a  ZWO EAF and a SV405CC OSC 14 bit TEC cooled CMOS camera, using an SVBONY SV165 guide scope with a QHY-5II-M guide camera. The equipment was mounted on a Celestron AVX mount.

The equipment capturing data

AstroDMx Capture captured the data, controlled the mount and the ZWO EAF via an INDI server running on the imaging computer indoors.

Imaging computer

As usual, the mount was placed on marks on the ground which quickly gives quite a good polar alignment if care is taken with the placement of the tripod feet.

The marks on the concrete base on which the mount is placed.

PHD2 was used for multi-star pulse auto-guiding and controlled by a separate Linux computer indoors.

AstroDMx Capture was used to send the scope/mount to Altair; with plate-solving to centre the star. AstroDMx Capture then controlled the ZWO EAF via the INDI server to exactly focus the star using an Angeleyes Bahtinov mask.

Altair being focused with a Bahtinov mask

The focus position was stored as a preset for this particular filter so focus can be easily achieved in the future when using the Altair Quadband filter.

Capturing with a Flip

AstroDMx Capture was used to capture 2 hours worth of data on the Omega nebula, M17. This was achieved by capturing 40 x 3 minute exposures. Eight images were captured (24 minutes) before an assisted meridian flip was used to re-acquire M17 and re-centre it in the field of view. The remaining 32 images were captured on the west side of the meridian.

AstroDMx Capture capturing data on the east side of the meridian

With a negative preview

Following the assisted meridian flip

AstroDMx Capture capturing data on the west side of the meridian

With a negative preview

In addition to the Light frames, Darks, Flats and Dark-Flats were used for calibration and stacking of the data.

The images were calibrated and stacked in Deep Sky Stacker (in a virtual Windows machine running on the Linux imaging computer) which is running Ubuntu Cinnamon Linux.

Note: AstroDMx Capture is a cross platform program that runs on Windows, Linux, macOS, Arm Linux (for the Raspberry Pi).

The stacked image was processed with The Gimp 2.10, Starnet++ for star removal and replacement techniques, Neat Image for noise reduction, PhotoScape X Pro and PaintShop Pro Ultimate 2023 for detailed colour processing.

Click on the image to get a closer view

M17, The Omega or Swan nebula

The image has been rotated into a more familiar orientation.

In conclusion the SV405CC camera performed flawlessly and AstroDMx Capture controlled the ZWO EAF precisely.

AstroDMx Capture is in the process of being updated with new features and updated SDKs. Also, the hardware, both computer and telescope plus focuser equipment is being updated and extended to support more equipment.

First Light for a new test rig

Introduction

These sessions involved the testing of the implementation of the ZWO EAF via INDI, the 66mm ED APO refractor the 2” SkyTech LPRO MAX broadband filter and also separately, an L-eNhance filter.

The equipment used

The equipment comprises a Stella Mira 66 ED APO refractor with a field flattener and Altair magnetic 2" filter holder with a SkyTech LPRO MAX broadband filter; a ZWO EAF and a SV405CC OSC 14 bit CMOS camera. For one session an Optolong L-eNhance duo-narrowband filter was used.

The equipment collecting data. AstroDMx Capture captured the data, controlled the mount and the ZWO EAF via an INDI server running on the imaging computer indoors.

Darks, Flats and Dark-Flats were also captured for calibrating the data.

Flats were captured using an adjustable brightness illuminated tracing pad and additional white plasticard filters.

Using the SkyTech LPRO MAX broadband filter

As usual, the mount was placed on marks on the ground which gives quite a good polar alignment.

PHD2 was used for multistar pulse autoguiding using an SVBONY SV165 guidescope with a QHY-5II-M guide camera.

AstroDMx Capture sent the mount/scope to Altair to focus with a Bahtinov mask and then M24, the Small Sagittarius star cloud.

AstroDMx Capture using Astrometry plate solving and centering Altair to within 5 arcseconds

AstroDMx Capture capturing 18 x 60s exposures of M24

The data were calibrated and stacked in Siril and post-processed in Siril and the Gimp 2.10.

M24 the Small Sagittarius star cloud with NGC 6603, IC1284, NGC 6590 and NGC 6589

AstroDMx Capture was used to send the scope/mount to NGC 6526. This is an insignificant patch of nebulosity almost midway between the Trifid nebula and the Lagoon nebula. This object was chosen to facilitate the composition of the image.

AstroDMx Capture captured 34 x 60s exposures, then performed an assisted meridian flip followed by 60 x 60s exposures of The Trifid and Lagoon nebulae.

With negative preview

The data were calibrated and stacked in Siril and post processed in Siril, and the Gimp 2.10 using star removal and replacement techniques, Neat Image, PhotoScape X Pro and Corel PaintShop Pro 2023.

The Trifid and Lagoon nebulae; M20 and M8 

Using a  SkyTech LPRO MAX broadband filter and also separately, an L-eNhance filter.

1 hour 45 minutes of data on the Eagle nebula captured by AstroDMx Capture  using a Stella Mira 66 ED APO refractor with a field flattener and Altair magnetic 2" filter holder with 30 minutes worth of 5 minute exposures through a SkyTech LPRO MAX broadband filter and 75 minutes worth of 5 minute exposures through an Optolong L-eNhance duoband narrowband filter.

AstroDMx Capture capturing data on M16 through an Optolong L-eNhance duoband narrowband filter.

With a negative preview

The data were calibrated and stacked in Siril and post processed in Siril, and the Gimp 2.10 using star removal and replacement techniques, Neat Image, PhotoScape X Pro.

Image from the SkyTech LPRO MAX broadband filter 

Image from the L-eNhance narrow-duoband filter

Image blended from the  LPRO MAX and the L-eNhance filters

In conclusion, The equipment all worked together with AstroDMx Capture and the SV405CC OSC CMOS camera. The Stella Mira 66 ED APO refractor with the field flattener produced very good star images with excellent colour correction and a good flat field. The ZWO EAF worked flawlessly with the refractor to which it was attached as shown HERE. AstroDMx Capture worked perfectly with the ZWO EAF via the INDI server and the scope was focused perfectly using a Bahtinov mask. The SV405CC camera worked well without issue.

 

Fitting a ZWO EAF to a Stella Mira 66 ED f/6 APO refractor

Introduction

The problem with many modern refractors is that whilst many of them are fitted with high quality engineered focusers, often with precision dual speed 1:10 fine focus adjustments; The suitability for electronic focuser fitment seems to have been a second thought; the result being a lack of standardisation. In the best cases, threads with blanking grub screws are provided on the underside of the focuser housing which hopefully will line up with slots in a motor-focuser attachment bracket.

The same criticism can be made of the design of electronic focusers in the sense that there is no standardisation of the design of the bracket for attachment of the motor-focuser to the scope focuser. This is a chicken and egg situation. Without standardisation of scope focuser housing, there can be no easy standardisation of motor-focuser attachment brackets. 

Some motor-focuser manufacturers produce brackets for specific telescopes, but there is a plethora of telescopes such that it would be impractical to manufacture brackets specifically for all of them. Some scopes can accept the bracket of a motor-focuser with no problems. One such example is the William Optics Zenithstar 81 APO that will accept a ZWO EAF bracket with no modifications to scope or bracket.

In this study we are preparing a Stella Mira 66 ED f/6 APO to work as a test scope for our Software AstroDMx Capture in combination initially with the SVBONY SV405CC 14 bit, cooled OSC CMOS camera and focused with a ZWO EAF.

We found that the focuser bracket can be firmly attached to the scope by making two modifications to the bracket and no modifications to the scope. This involves drilling out a hole in the central elongated gap in the bracket to allow the wider of the supplied attachment screws to pass through to a suitable grub-screw blanked thread on the scope focuser housing. The second modification to the bracket involves using a hacksaw to cut through an outside rail and then using a file to remove a small amount of aluminium to accommodate the rather large focus lock knob on the scope.

The modifications needed for the bracket

The bracket is symmetrical, so it is possible to see the portion that has been removed by looking at the other side of the bracket.

Close-up of the fitted bracket and EAF

The large focus lock knob has been easily accommodated by this simple modification.

The ZWO EAF fitted to the Stella Mira 66 ED f/6 APO refractor

Of course, the focus lock is not engaged from now on because the EAF will effectively lock the focuser in whatever position the focuser is.

The rest of the rig comprises a x1 field flattener and an Altair 2” magnetic filter holder plus the camera and spacers. Fine adjustment of the spacing will be made when the scope goes into use.

In conclusion, the ZWO EAF bracket was easy to modify to enable the Stella Mira 66ED APO refractor focuser to accept it with no modifications to the scope.

Case cooling a Player 1 Mars-C ll, 12 bit OSC CMOS camera

 

Introduction

We previously reported an experiment to case-cool a ZWO ASI 178MC 14 bit OSC CMOS camera. That experiment involved a Yodoit K6 Portable Magsafe Magnetic Mobile Phone TEC Cooling LED Radiator costing under £20 on Amazon UK attached to the flat back of the camera by an adhesive metallic disk to which the cooler could attach magnetically.

The current experiment was an attempt to case-cool a Player 1 Mars-C II 12 bit OSC CMOS camera using a similarly attached Magnetic Mobile Phone Radiator, Refrigeration Turbine Phone Cooling Fan that was purchased from Amazon UK for less than £12.

The metal disk is stuck to the back of the camera. However, the central part of the back of the camera is depressed slightly so that the metallic disk only makes contact with the raised part of the camera back towards the edges. Nevertheless, there is significant contact for heat exchange to take place.

The Mars-C II camera does not feature passive cooling which is a feature of some of the larger format Player One cameras such as the Apollo-M/C, Apollo-M Mini, Saturn-C SQR, Uranus-C and other models. The inbuilt passive cooling system of these cameras facilitates the transfer of heat from the sensor to the camera back. The Player 1 ACS (Active Cooling System) is a fan cooler that bolts onto the back of the camera, but does not involve TEC cooling. Player One states that their ACS does not work with cameras not supporting passive cooling. That makes this TEC plus fan cooler system employed in this experiment an important investigation.

The cooler is held magnetically to the back of the camera by the adhesive disk. It would be possible to place a thermal pad in the recessed area behind the metallic disk to facilitate heat transfer from the back of the camera. We did not employ a thermal pad. Player One employs such a thermal pad in their ACS.

When powered up by means of a USB-C connector and a USB lead to a mains/USB 5v adapter coloured LEDs illuminate the cooler with cycling colour displays.

Capturing long exposure, 16 bit dark images at different camera temperatures

Screenshot of AstroDMx Capture capturing 20s exposures at 500 Gain at 28 degrees C

Screenshot of AstroDMx Capture capturing 20s exposures at 500 Gain at 18.1 degrees C

There was considerably more noise when the camera was at 28 degrees C which it warmed up to over time after the camera was turned on.

A dark image captured at 28 degrees C

A dark image captured at 18.1 degrees C

Both images were stretched by an identical amount to reveal the noise that was present.

Measuring rates of temperature change in the case-cooling setup

The camera was connected to AstroDMx Capture and was set to 16 bit 20s dark exposures at Gain 500. AstroDMx Capture was set to refresh the display of the camera temperature every 5 seconds. The temperature was recorded at intervals until a maximum value was approached. Then the cooling was turned on and the temperature was continued to be recorded until a minimum was reached.

It can be seen that temperature change is a relatively slow process and it took about an hour for the camera to reach a maximum value. Of course, in use, the cooler would be turned on immediately when the camera was connected, so the cooling time would be less than from a camera at its maximum temperature. Cooling time will depend on the ambient temperature when used in the field.

An unknown at the present time is whether the optical window of the camera would eventually become covered in dew and how this would be affected by humidity, or even worse (and possibly dangerous to the camera itself), whether dew would start to form inside the camera, or whether the heat generated by the electronics would prevent this from happening.

Clearly the cooler would be turned on at the outset so that the camera could be cooling down whilst the target is being acquired, the exposure and gain determined, focusing and auto-guiding set up.

We hope to test this case-cooling arrangement in the field in the near future.

Any attempts to reproduce the work done here should be done with caution as there is the caveat that any adverse effects that might affect the camera are at this time unknown. For this reason we are NOT recommending this procedure at this stage.