1.About the Target M81 and M82:
1-A: M81:

• M81 is one of the brightest galaxies in the night sky. It is located 11.6 million light-years from Earth in the constellation Ursa Major and has an apparent magnitude of 6.9.
• Through a pair of binoculars, the galaxy appears as a faint patch of light in the same field of view as M82.A small telescope will resolve M81's core.
• The galaxy's spiral arms, which wind all the way down into its nucleus, are made up of young, bluish, hot stars formed in the past few million years. They also host a population of stars formed in an episode of star formation that started about 600 million years ago. Ultraviolet light from hot, young stars is fluorescing the surrounding clouds of hydrogen gas.
• A number of sinuous dust lanes also wind all the way into the nucleus of M81.The galaxy's central bulge contains much older, redder stars. It is significantly larger than the Milky Way’s bulge. A black hole of 70 million solar masses resides at the center of M81 and is about 15 times the mass of the Milky Way's central black hole. (Wrote by NASA)

1-B: M82:

• M82 or the Cigar galaxy, shines brightly at infrared wavelengths and is remarkable for its star formation activity. The Cigar galaxy experiences gravitational interactions with its galactic neighbor, M81, causing it to have an extraordinarily high rate of star formation — a starburst.
• Around the galaxy’s center, young stars are being born 10 times faster than they are inside our entire Milky Way galaxy. Radiation and energetic particles from these newborn stars carve into the surrounding gas, and the resulting galactic wind compresses enough gas to make millions of more stars. The rapid rate of star formation in this galaxy eventually will be self-limiting. When star formation becomes too vigorous, it will consume or destroy the material needed to make more stars. The starburst will then subside, probably in a few tens of millions of years.
• M82 was discovered, along with its neighbor M81, by the German astronomer Johann Elert Bode in 1774. Located 12 million light-years from Earth in the constellation Ursa Major, M82 has an apparent magnitude of 8.4 and is best observed in April. Although it is visible as a patch of light with binoculars in the same field of view as M81, larger telescopes are needed in order to resolve the galaxy’s core. (Wrote by NASA)

2.The C.L.A.P.T.
The China Long-Focal-Length Astro Photography Team (abbr: C.L.A.P.T.) was established in 2024 and consists of 17 astro photography enthusiasts from China. Members of the team are either amateur or professional photographers who use long focal length telescopes at remote observatories within China for their shoots. The team usually plans to take 1 to 2  astro targets every month, and team members can freely sign up to participate in Co- Shoots projects. Before the shoot, members will unify the coordinates and shooting parameters, and each of them will compile and sharing  data and generate a Master file after shooting.

3. CLAPT Team Members of Squad M81xM82:
1. Weitang Liang, from TaiYuGe Obs.
2. Barry Li from Daocheng Galacier Obs.
3. Yanzuo Liu from Daocheng Galacier Obs.
4. John C.Yu from Daocheng Galacier Obs.
5. Steven Zhang from Daocheng Galacier Obs.

4. Integartion Info
The total integation is about 280 hrs,  consisting of the following data taken by 5 team members of the squad for each of the two panel. About 65%~70% of the collected data was used in the final integration for each channel.So, the effective integration time is about 188 hours.

4-A, Panel 01 (M81 Bode's Galaxy), Panel Sum = 86.6 hrs

1. Lum = 36.92 h
2. Red = 8.33 h
3. Green = 8.33 h
4. Blue = 8.33h
5. NB Ha = 24.67h

4-B, Panel 02 (M82 Cigar Galaxy), Panel Sum = 194.92 hrs

1. Lum = 52.25 h
2. Red = 31.75 h
3. Green =25.92 h
4. Blue = 26.75 h
5. NB Ha = 58.25 h

Each of us contributed more than 35hrs of raw data ( before selection)  About 50% of NB Ha data was collect under 60% or high moon phase, with relatively low SNR on each single frame. Tabel below shows how much data was taken by each of us. (A/O stands for Antlia or Optolong)


5.Equipment
     5-A: Barry's Set 

1. Telescope: William Optics 10'' f/8 Ritchey-Chretien Truss Tube
2. Camera: ZWO ASI2600MM-Pro
3. Mount: Sky-watcher EQ8r-Pro
4. Filters: Antlia Dark Series LRGB, 3nm Ha
5. Flattener: William Optics Dr. Flat Master 0.8x for GSO RC (12"-16") (Flat-RC)
6. Location: Daocheng Glacier Observatory, Sichuan,China.

     5-B: John's Set

1. Telescope: William Optics 12" f/8 Ritchey-Chretien Truss Tube
2. Camera: ZWO ASI6200MM-Pro
3. Mount: iOptron CEM120EC
4. Filters: Antlia V Pro LRGB, 4.5nm Ha
5. Flattener: William Optics Dr. Flat Master 0.8x for GSO RC (12"-16") (Flat-RC)
6. Location: Daocheng Glacier Observatory, Sichuan,China.

 5-C: Weitang Liang's Set

1. Telescope: Celestron 14'' EdgeHD + Optec SMFS
2. Camera: Moravian C3-61000EC Pro
3. Mount: Paramount MX+
4. Filters: Chroma LRGB +5nmHa, Moravain EFW-3L-9
5. Flattener: Celestron 0.7x for C14HD
6. Location: Taiyuge Observatory, Hebei,China.

5-D: Yanzuo Liu's Set

1. Telescope: 10" f/8 Ritchey-Chretien Truss Tube
2. Camera: ZWO ASI2600MM-Pro
3. Mount: AZ-EQ6
4. Filters: Antlia V Pro LRGB, 4.5nm Ha
5. Location: Daocheng Glacier Observatory, Sichuan,China.

     5-E: Steven's Set 

1. Telescope: GSO 12'' f/8 Ritchey-Chretien Truss Tube
2. Camera: ZWO ASI2600MM-Pro
3. Mount: iOptron CEM120
4. Filters: Optolong LRGB, 3nm Ha
5. Flattener: SharpStar RC308 focuser and reducer-flattener Kit (RC2508)
6. Location: Daocheng Glacier Observatory, Sichuan,China.

4. PreProcess and Integration of 5 different FOV
After gathering all the data the squad taken, preprocess and integation was performed by John Yu with WBPP on PI, and AstroPixelProcessor (abbr. APP), respectively.

To accommodate these sets of data with very different FOV and resolution without leaving obvious defect on Master files (such as dark or noisy region on the edge of overlapping area, or unblacnced background brightness) while maximizing the FOV taken by WORC12+6200MMP was really a hard one. John has tried his best repair those defects using any method he found, including NSG, DBE, MSGC, etc.,  while the result was not satisfying. After few attempts, John achieved to find a way integrating all these data without leaving any defects. Here attaches how the fov looks like approx. 


4-A The Mix-FOV Integation Method

1. Calibration, StarAlignment , NSG (Normalized Scale Gradient, optional) data and Integation per set of data sort by contributors. You can also use WBPP (cali, register, inte) with autocrop on.
2. DBE or Gradient Correction on each channel & each contributor. For this data, that means 5*4=20 times of GC.
3. Do StarAlignment Again with FOV of WORC12 & 6200 as reference, performes integations and crop. You can also use WBPP with AutoCrop confirmed. Then performe DBE or Gradient Correction for the MasterLight you get with maximized SNR and overlapped area.
4. Load all masters you get from step 2 and 3, to AstroPixelProcessor, set MasterLight of WORC12 & 6200 as reference, select SNR for weighting, adjust parameters and run Integation. Note: Enabling LocalNomorlization in APP are NOT suggested.
5. If you follows all instructions, then you shall have a decent result, with highest SNR on overlapped regions and smooth background.

Special thanks to:  Grapeot, who kindly shared his briliant method of adding stretched Ha data to LRGB using Photoshop. He has uploaded tutorial on YouTube and Bilibili. 

Hope that you guys like this image!

C.S.

Barry, Abner, John, Yanz and Steven
C.L.A.P.T.