ZiHao

I am quite sure that the equations will be the same for other quadrants. I will try to derive it later.. Hi Victor. Yes, it is astropy. I tried looking for procedures for lsr correction but didn't manage to get any, and it sounds like a complicated task to me, so luckily astropy has all these built in functions!

The formulae should be correct, attached is the derivation.

c=299792.458 rest_freq=1420.40575e6 #freq=frequencyarray velocity=c*(1-(freq/rest_freq)) corrected_vel=velocity*u.km/u.s rv=c*((rest_freq/rest_freq)-1)*u.km/u.s t = Time(, format='mjd') loc = EarthLocation(lon=,lat=,height=) ra=*u.deg dec=*u.deg sc = SkyCoord(ra,dec) vcorr = sc.radial_velocity_correction(kind='barycentric', obstime=t, location=loc) rv = rv + vcorr my_observation = ICRS(ra=*u.deg, dec=*u.deg, \ pm_ra_cosdec=0*u.mas/u.yr, pm_dec=0*u.mas/u.yr, \ radial_velocity=rv, distance = 1*u.pc) new_rv = my_observation.transform_to(LSR()).radial_velocity corrected_vel=corrected_vel+new_rv Attached above is my attempt on LSR correction, I chose rv as zero so it is easier to add the final rv (new_rv) to the frequency array as I find it takes quite long to compute for individual frequency point. I don't think there will be significant difference in the final result using this method, I will check this again later. You can try the code above, just enter the corresponding info required. I have checked this with the LAB survey with my limited data at hand. The main peak in my data is around +9km/s, which agreed with the survey.

Very interesting idea, especially the color that shows the amount of redshift. I think the equations used to plot the cartesian view of the milky way applies for all cases, you will get two positive r due to the two intersection points along the line of sight for quadrant I and IV. For quadrant II and III, I believe you will get one negative r and one positive r, I might be wrong. For the two positive values of r, seems like we have to reject the data as shown in your attached pdf, I wonder how can we further validate the values. It might be a good idea to cross check your spectrum with the ones from LAB survey, you can download the data in the link below. I have attached a general illustration of roughly how the arrangement of colored dots should look like, the picture is from DARA https://www.youtube.com/watch?v=RQiLMxQHxr8&t=2946

https://astronomy.stackexchange.com/questions/41196/looking-for-a-routine-to-correct-for-local-standard-of-rest-lsr Hope this helps. I have tried this routine by manually entering the individual frequency value, it matches with the spectrum from the LAB survey.

https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ Scroll down and you will see the picture. But if you were able to use the bias tee, most likely it is genuine. Then the spikes should be interference.

Hello Steve, When I was using the clone rtlsdr, I used to take a reference spectrum at another frequency, where there is no hydrogen line signals, and subtract that with the spectrum with hydrogen line signal. It should be clear that whether or not there's a signal, despite the clone dongle having a lot of noise spikes. With the genuine rtlsdr, I am trying to fit a polynomial curve to the source spectrum to avoid adding extra noise when subtracting. The result I posted is manually done by eyeballing the curve that fits the overall shape of the spectrum best, hopefully the process can be automated soon. I averaged about 200000 spectra or 2-3 minutes of exposure. Depending on your system temperature, a shorter exposure time should be good enough to detect the signal. All these are done in python with the wrapper pyrtlsdr. A good way to check if you have detected is do to a 24 hours drift scan like what you've mentioned. When the milky way passes through the beam, signal rises, when it exits, signal falls. I have attached the gif below, this is done with the clone rtlsdr, lots of spikes. You can try to examine the raw spectrum, the spectrum before baseline subtraction. There should only be a single DC spike at the center of the spectrum, and the rest could be RFI that you can try to identify. Another good website to verify your signal is here https://www.astro.uni-bonn.de/hisurvey/euhou/LABprofile/index.php, your peaks should be very similar to to simulated spectrum. Zi Hao

Hello Steve, I made the dish myself, the idea is developed by JA6XKQ. No pre-bending work required, the structure will form by itself. You are right, I can see a little bending when I connect the cable to LNA so seems like I have to order a right angle sma as well. I haven't tested the waveguide with a vna, so most of it is not really optimized for hydrogen line I believe. The user guide for the bias tee is here https://www.rtl-sdr.com/rtl-sdr-blog-v-3-dongles-user-guide. There should always be a actual powered device connected to the sdr before turning on the biast. So always check you have the LNA connected. When it is turned on, you should see a white led light on your LNA. Links for the geodesic dish if you are interested: https://www.reddit.com/r/RTLSDR/comments/7ksfba/diy_parabolic_dish_reflector_antenna/ Zi Hao

Hello Steve, The genuine rtlsdr just arrived few days ago, so you asked at the right time! I was using a clone rtlsdr which has a lot of noise before this, and the genuine one shows a lot of improvement. I am using a very simple python script with pyrtlsdr for data acquisition, this is similar to Victor's method. My setup is LNA-->5m LMR400-->Rtlsdr-->Rpi. Still working on a cleaner baseline for easier data processing and hopefully able to mount the dish on my equatorial mount soon.

Nice work. There's this excel sheet provided here http://www.setileague.org/hardware/feedchok.htm that calculates the feedhorn dimensions. I have built a 1.4m geodesic dish recently, using a feedhorn with diameter 145mm and length 180mm without choke. I didn't follow the exact length as given in the excel spreadsheet to minimize the weight as much as possible. The length of the feedhorn should be twice or three times as long as the distance from the probe to the end cap as a rule of thumb according "The Radio Sky and How to Observe it" by Jeff Lashley. feedhorn.xls

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.

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.

An open cluster containing about 100 stars located in the south of Sirius and visible in finderscope under bright skies. 25 minutes of data.

It is visible even in a 1 second image and clearer as it gets higher.

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

Very interesting results Victor! Can't wait to see more reports like these.

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.

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!

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.

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.

Great job to all participants! Clear Skies

This is from ZWO. Hope it helps.

Second attempt: Really like the dark dust!

Thanks for the data! Everything done on PS and Starnet.

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.