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Everything posted by ZiHao

  1. Hello, I am planning to build a shoe box CD grating with DSLR+18mm kit lens to analyse the spectrum of different light sources and hopefully someone will share their thoughts on the design. I am not sure about the number of lines per mm of the grating, maybe next week I will buy a laser to calculate the value but let's assume it's 625 lines/mm. I calculated the length of entire spectrum which is about 2.4cm and not sure whether this has a direct relationship with the sensor size or not, which is 2.35cm long. Any help will be appreciated.
  2. Perhaps more to the artistic way of presentation this time, this is shot on 26th February, a composite of two images, 0.5 second exposure for the branches from a forest reserve and 1/1000 second for the Moon. The interval between the two shots is about 30 seconds, which I took to change the focus of the scope and mount tracking is on if I am not mistaken. The two images are then combined on PS with the opacity of the longer exposure image lowered followed by some brightness adjustments.
  3. An open cluster containing about 100 stars located in the south of Sirius and visible in finderscope under bright skies. 25 minutes of data.
  4. It is visible even in a 1 second image and clearer as it gets higher.
  5. M64 Black Eye Galaxy 4 hours of data shot using Skywatcher 150/750 and D5300 in Bortle 8 zone. Using a black and white image this time to hide away the color gradients possibly caused by light leaking into primary mirror, nevertheless I should pay more attention to this problem since I started imaging, as it worsens everytime I pushed the image harder. DSS, PS
  6. Very interesting results Victor! Can't wait to see more reports like these.
  7. North is up. SW150p, ASI120MC, 2x Barlow,EQ3 Pro. 300*1s stacked on Registax. Couldn't resolve it visually when taking a brief look with 10mm plossl and 2x Barlow at around 8.30pm, perhaps I should wait for the scope to be thermally stable first, before sliding in the camera in a hurry to take images. Sirius B is clearly discernible in a 1 second frame as it gets higher. The stacked image was heavily stretched in PS to reveal the faint background stars, to correct for the offset in position angle by rotating the image. Eventually, Sirius B is measured to be 64.5 degrees from north approximately, which is a 1.8 degree offset from 66.3 degrees obtained from skysafari. The distance from Sirius to Sirius B is 13" from the image, compared to 11.2", so about 3.5 pixels off.
  8. Very interesting information, only found out about SA100 few months ago. Wanted to get one of these immediately but have to be patient till the stock arrived in FLO!
  9. There's one in Borneo island, 1646km away at 89.5Mhz. But at 89.6Mhz, there is a station as well about 100km away, when I tune to this frequency with my FM radio mobile app, there is only static noise. Not sure whether this will affect the results. Does the transmission power matter a lot? If yes, what's usually the minimum for meteor detection? I saw a youtube video that someone managed to receive the signal from the same station in Borneo (89.5Mhz) at about 4000km away.
  10. Hello, Recently I got interested in radio astronomy simply because clear skies are way too rare! So I plan to dip my toes in the water by doing radio meteor detection. Many on the forum are doing this by detecting the radio waves from France reflected to the receiver. In Malaysia, I think this is unfeasible, so do you guys know any transmitter in Asia that emit high power continuous wave? Not sure whether this is the key word, if there are other alternatives, please do let me know. Thanks.
  11. Great job to all participants! Clear Skies
  12. Thanks for the data! Everything done on PS and Starnet.
  13. First time processing narrowband images and thank you IKI and FLO team for the amazing data. Software used: PS and StarNet++. Workflow: 1. Auto stretch Ha, Oiii, Sii separately in Camera Raw filter. Equalize function from Olly was applied to the three channels and denoising done for Sii and Oiii channels in Topaz Denoise plugin. Lastly, sharpened using Unsharp Mask. 2. Each channel is imported into StarNet++. Starless images combined as SHO in PS. 3. Gentle stretch to the image after some light denoising. The bright core is masked with the original Sii channel to recover the details. 4. Selective colour and gentle sharpening. 5. Results from Step 1 were combined as SHO as well to obtain the star field using difference blend mode. Star field is then overlaid on top of the image after Step 4 using screen blend mode. 6. Stars made a little smaller using color range tool and minimum under filter tab.
  14. Thanks. 35 lights and IIRC, 20 flats and no darks were taken. Generally people only take around 30 darks. I think you should try with maybe more/less darks or even without them to stack with your raws to see how much it helps the image.
  15. So I am planning to make a dew heater for my camera len using resistors wired in parallel, then distributing them around the circumference of the lens. Diameter of lens: 65mm Total power output: 6W Power Supply(powerbank): 5V, 2A, 20Ah Resistance for each resistor: 120 Ohm Resistor power rating: 0.25W Power output for each resistor: 0.21W Current drawn: 1.21A Number of resistor required: 29 Will probably insulate the wire with tape, and wrap the resistors in cloth around the lens. Is 6W too much or sufficient for this use? Any suggestions? Thanks.
  16. Hi, Yesterday a partial solar eclipse happened here so I took a few pictures using a DIY solar filter with the provided dust cap. And the center seems to have a blurry circle or reflection. Any idea? I don't remember this happening to the image when I use a full aperture filter which I wasn't using this time, was worried that it may fall off. Thanks.
  17. Shot with SW150/750, ASI120MC and 2x Barlow. Stacked on AutoStakkert!, edited on Registax and PS. Hold your phone away from you, it will look better
  18. Tried it, doesn't work. I selected the ZWO USBST4, the slew buttons just don't work. In PHD2 Manual Guide everything is okay as the option 'On Camera' is available. I guess EQDIRECT cable is necessary then.
  19. I have seen a lot of questions about this topic but didn't get a clear answer. Is there a way that I can dither without guiding using APT and PHD2? I am using ST4 cable now and mounting a DSLR + kit lens on my EQ3 Pro to do normal sidereal tracking (maybe dithering is redundant at short focal length, say 24mm?) Will disabling the RA and DEC corrections in PHD2 still allow dithering? Because I don't need guiding for the widefield setup and not planning to mount the guidescope on top either. Thanks in advance.
  20. Stars seem to 'travel' faster on the celestial equator than the stars situated at the poles. Why is this? Is this just a perspective problem?
  21. I think if you want to avoid light pollution, travel to Mersing which I believe is close to your location.
  22. Anyone done astrophotography with this guidescope? Sounds like a stupid idea, but being limited on budget, I was hoping to mount this on my EQ3 pro instead of the heavy Newtonian reflector. It costs only 120 dollars, a really cheap refractor. What do you think?
  23. I am using a DSLR and only takes bias frames and flat frames but no darks as the temperature I believe doesn't match. I heard that if you already have bias frames or when the flats are of short exposures, you don't need dark flats. But IMO, usually dark flats aren't necessary. What do you think?
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