Jump to content

Banner.jpg.b83b14cd4142fe10848741bb2a14c66b.jpg

SteveBz

Members
 View Profile  See their activity

  • Posts

    1,103

  • Joined

  • Last visited

 Content Type 

Posts posted by SteveBz

    Calibrating a LowSpec3.0 Spectrum of Alpha UMa

    in Radio Astronomy and Spectroscopy

    Posted

    9 minutes ago, robin_astro said:

    Provided the actual width of the line is significantly narrower than the resolution then yes this works but Ha alpha can be wide particularly in some stars eg like in Vega so you really need a line which is known to be very narrow. Try measuring the width in some of the narrow metal lines in your spectrum and see if this gives a higher resolution or  sky lines (natural or from light pollution) or from narrow lines in the calibration lamp provided it illuminates the spectrograph well (Note a single small lamp at the telescope aperture will not work for this as it like  a very high focal ratio pinhole camera and gives a perfect in focus image even when you are out of focus! If doing this using neons arrange 3 or 4 of them round the aperture edge)

    Cheers

    Robin

    Great advice.  The lines at 639 are much narrower and I get nearer 9k.

    I bought 5 neon lights.  I thought I'd 3d print a kind of ring round the rim to embed them in it.

    • Like 2

    Calibrating a LowSpec3.0 Spectrum of Alpha UMa

    in Radio Astronomy and Spectroscopy

    Posted

    On 25/05/2023 at 23:52, robin_astro said:

    If you are looking specifically around H alpha at high resolution a simple neon lamp will do the job. Point the telescope at a bright A or B star and look for H alpha which will be obvious as there will be no other strong lines near it. Then when you have it centred take a neon lamp as a refence and identify the lines from for example Christian Buil's website here

    http://www.astrosurf.com/buil/us/spe2/hresol4.htm

    Cheers

    Robin

     

    Hi Robin,

    I just saw that.  It's pretty much what I did.  I found an old Philips low energy fluoscent bulb and got this:

    image.png.69edf327481ee4d64831b3fcae76c5a6.png

    image.png.793d0b0b88900bb0da481b025d45b816.png

    Which resulted in this:

    image.png.09a885eb083ce54aace0b5a0d7ac7f85.png

    I calculated the R number. The half height width for Ha seems to be about 0.16 so R=656/0.16 or about 4000. Is that right?

    Now I need to improve the process with flats, darks and biases etc.

    I've also bought soem neon lights, so the calibration will get better.

    Tx

    Steve

     

     

    Calibrating a LowSpec3.0 Spectrum of Alpha UMa

    in Radio Astronomy and Spectroscopy

    Posted

    The issue I'm having is matching up lines when the resolutions are different as close together spikes can become joined up and mislead the eye.

    I think I need an alternative source for calibration.  I may try to calibrate with the Fraunhofer lines from the Sun, or maybe a luminescent bulb from Wickes.  Stars don't come out until nearly midnight now, so that's a bit painful. :(

    Steve.

    Calibrating a LowSpec3.0 Spectrum of Alpha UMa

    in Radio Astronomy and Spectroscopy

    Posted

    Hi Fellow Astronomers,

    I'm trying to get the hang of a LowSpec3.0 spectrometer.  The other night, everything fell into place and guiding on the slit worked (after a bit of star-hopping). The slit is set to 20 um and I took 10 x 20 second exposures, stacking in Bass.

    Here is a spectrum of Alpha UMa in the H-alpha region:

    image.thumb.png.071e846c1af07ea07721c97bf4589ed5.png

    I hope the big dark line is the H-alpha line, but I don't know the names of any of the other lines so that I can calibrate it.  Any ideas?  Here is a rough chart from Bass, after removing hot pixels except one at about 540 px:

    image.png.9aa1e4c6a3fae596f5ad43805faabba1.png

    Thanks for your thoughts.

    Kind regards,

    Steve.

    Fraunhoffer lines, which way round are these?

    in Radio Astronomy and Spectroscopy

    Posted

    16 minutes ago, robin_astro said:

    Here is mine with a LHIRES (much reduced) Unfortunately I lost the full size version.

    http://www.threehillsobservatory.co.uk/astro/spectra_28.htm

    I suggest moving to the red until you see the very distinct Oxygen telluric band pattern (at the end of my spectrum) and then work back from there.  H alpha is broad and strong, the Na D lines are distinct but some of the weaker lines round there are telluric water lines so dont always show clearly. The Mg triplet should also be clear. At the violet end you should see two broad strong Calcium H J lines before the sensitivity of the camera runs out

    Cheers

    Robin

    Did you take this with a colour camera, or add the colour afterwards?

    Any ideas on repairing a (slightly!) blown motor board ?

    in DIY Astronomer

    Posted

    On 03/05/2023 at 18:16, malc-c said:

    Seeing how popular this thread has become over the years, and given that newer generations of mounts now have ARM based control boards in them,  I've been thinking of how best to try and help out others who find themselves in the same situation as the OP.  The idea is an exchange service, where someone with a faulty board can send me their faulty board(s) and in return will received a replacement that I've already repaired and tested.  This means less downtime for the SGL member, and takes the pressure off me to get the board fixed and returned quickly.  There will be a cost involved to cover the parts, return postage and possibly a pint or two for my time, but it will still be less than half the cost of a new replacement.  The only drawback with this idea is that I need "spare" donor boards to start the ball rolling.

    To this end I would like to thank @SteveBz for his kind donation of a faulty EQ6 board and handset (plus associated cables) after it all stopped working one evening.  Steve had already been out and purchased replacements, so rather than the parts end up in the bin he kindly started the process by donating them to the cause.

    So here's the first fix prior to clean up. 

    eq6.jpg.260598d76abb211716b8f174d2ffb924.jpg

    It's been a while since I've last repaired a board so I was a bit rusty, and a few red herrings resulted in me straying down the wrong direction until the penny dropped and a likely cause was resolved.  After a visual inspection there was nothing glaringly obvious so an EQDIR cable was attached and the board powered on.  Communications were tested and sending :e1 and :e2 to the board resulted in no response form the board.  I first thought the issue might b the diodes, but in a bid to remove the two diodes to test out of circuit both were damaged, mainly as they were a sort of hybrid between through hole and surface mount component.  These were replaced with 1N4148s (through hole, but surface mounted to the pads).  I knew it wasn't going to be that easy, so both PIC microcontrollers were removed (using hot air gun), and the board cleaned ready for the replacements.

    The EQ6 firmware was downloaded and then converted to HEX.  I had two 16F886's left in my storage box so programmed them with the remastered HEX file.  The PICs were then soldered in place and the board tested.  Now this is where my miss-direction started.  I came across a very comprehensive test program that basically simulates a handset and sends the strings of commands to interrogate the motor board.  So I tried this out and it fell over after sending the :e1 command to get the firmware version back from the PIC associated with the RA axis.  As it didn't get a response it halted running the rest of the commands rather than testing the second PIC.  If it had then it would have been clear that the new PIC controlling the DEC axis was fine and responding.  So thinking that the issue was with the TX (transmission line from PIC to PC) was still faulty on both PICs more testing was needed.  I spent a good day trying to trace out possible causes.  All voltages proved to be OK, including the 33v line for the stepper motors, so it wasn't a case of the PICs not running due to a supply issue.  I also replaced the 1N4148's thinking that maybe I was unlucky and had one or two duff ones... 

    Anyway, I took the dog for his daily walk and whilst he spent his time sniffing every bush and tree my thoughts were on the repair of the board, as I had clearly missed something.  When I got back home I thought I would try an alternative means of testing and opened up a standard windows terminal.  I then sent :e1 and nothing came back, but sending :e2 returned  the firmware version... so I had a half working motor board.   I checked all the connections once more and the solder joints were fine.  I then thought that possibly the TX line was fine, but the issue was with the RX line.  The RX line that receives the commands from the computer or handset has only one component in series with it, a ceramic inductor, after which the traces go straight to the RX pins on both PICs.  Now I know the tracks to the DEC axis must be good as it was receiving and responding to the commands sent via the terminal application, so the fault could be the traces that run from the inductor to the PIC responsible for the RA axis.  I spent a good few hours trying to "bell out" the traces, but on a four layer board fully populated  it was impossible to discover where the brake was.  My thoughts are that it's internal,  so I simply bridged the link between both PICs with a wire and then tested using the terminal application.  Finally it responded and I could then test the communications using the synta test application.

    eq6log.png.7097eb976ddf8dd3d475451a66fcdfaf.png

    This time the test application ran the full script and not only reported the firmware version, but also confirmed the board was an EQ6 and provided the mount specifics for the gearing and steps per RA revolution etc.

    The board was then cleaned up and is now the first board to become part of this exchange program.  I also have a second EQ6 board donated to the cause.  This one again reported "No response Both axis" when the handset tried talking to it, and on inspection there is a nice chunk blown out of the DEC axis PIC microcontroller.  I'm hoping that replacing both PICs will resolve this, and that this board hasn't got internal damage like the other.  This board will have to wait as I have had to order some more 16F886's before getting the soldering iron back out.  

    Naturally this program will only work if the board being sent in for exchange can be repaired. If the board has a glaring burnt hole in it, or some other physical damaged then regretfully I won't be able to help.  Also it is dependent on people who have already purchased replacements to donate their faulty boards to me.  If I don't have a repaired board to exchange then a normal repair could be considered.

     

    Great job Malcom. 

    pointing with a radio telescope?

    in Radio Astronomy and Spectroscopy

    Posted · Edited by SteveBz

    I didn't see that version, but a previous or maybe the original, used an EQ6.  I love their products.  I just don't have that sort of money.  21k!!!  The one in my profile picture used an EQ5, and star alignment was indeed a problem.  That's why I switched.  At one stage I thought about mounting a finder scope on it.

    I probably spent £100 on mine and then spent a month or two plotting the spiral arms of the milky way.  Each observation is an entire project, for me at least.

    But if you are planning to buy one of these, it would be amazing.

    Good luck, and it doesn't even matter if it's cloudy.

    Kind regards

    Steve.

    • Like 1

    pointing with a radio telescope?

    in Radio Astronomy and Spectroscopy

    Posted

    Hi,

    It depends on your design.  On mine the Earth is my RA and I only change DEC.  I can't track. 

    image.jpeg.c7ce2b26f3cbfceaacc2d49fd003288e.jpeg

    The width of your beam is 1.22 * lambda/width - in radians,  or about 10 degrees for my dish, which is 1.3 m wide.

    http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/Raylei.html 

    Then I use an inclinometer to track DEC:

    https://www.amazon.co.uk/Trend-DLB-Digital-Level-Black/dp/B01HF9FJJU/ref=asc_df_B01HF9FJJU/?tag=googshopuk-21&linkCode=df0&hvadid=232122755890&hvpos=&hvnetw=g&hvrand=10905520700690284117&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006661&hvtargid=pla-421592053330&th=1

    image.thumb.jpeg.71f559b3b2d883fb65a2852553284d1c.jpeg

    Because of my resolution I sky-scan and adjust by 10 degrees per 24 hours.  In reality the inclination gives Altitude, so I need to adjust it.  Overhead is my latitude so DEC = INCL - (90 -LAT).  You can see it's right because if INCL = 90, then DEC = LAT, and that seems right.

    Post your design here and let's look.

    Kind regards

    Steve.

     

     

    • Like 1

    New Skywatcher EQ6 Motherboard with USB

    in Discussions - Mounts

    Posted

    Hello folks,

    My old Skywatcher board with the D9 plug just died (and seemed to take the SynScan handset with it) and I replaced it with a new motherboard from RVO with a USB port and USB cable and no EQmod cable.

    I'm using INDI/Kstars to connect to the EQ6 with the EQMOD driver.  However, the EQmod driver can no longer see the new card and nor can the SynScan driver (although I imagine if I used the SynScan HC cable into the handset it could). Does anyone know what INDI driver I should use for the new EQ6 USB connected board please?

    Kind regards

    Steve.

    Call for Images of 3/4 inclined spiral galaxies

    in Radio Astronomy and Spectroscopy

    Posted

    7 hours ago, beka said:

    Hi SteveBz,

    Maybe you can try on the NASA/IPAC Extragalactic Database. There are fit images you can download.

    Cheers.

    HI Beka,

    Thanks for this.  I need images that I can ask people about their production (eg is the image calibrated but not stretched).  I'll have a look and see if they match some of the images I already have.  If they do that's great.

    Kiund regards,

    Steve.

    Call for Images of 3/4 inclined spiral galaxies

    in Radio Astronomy and Spectroscopy

    Posted

    Hi Folks,

    In my on-going search for dark matter (nothing so far, sorry :)).  I'm trying to replicate the theoretical rotation curve lines for inclined spiral galaxies like m31 and m81 and I was wondering if anyone has some images of NGC7331 or M109 or similar.  Ie not edge-on and not face-on.  This is what I'd like, pretty please:

    • single stacked mages of any spiral galaxies; 
    • 3/4 inclined, not face-on or edge-on;
    • Calibrated frames with biases, darks and flats, and stacked luminescence ie not stretched, cropped or otherwise processed;
    • .fits, .fit or .fts file;
    • the larger the better;
    • Nicely focused.

    Thanks so much.

    Kind regards,

    Steve.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.