Astro Photos

  • Sun Images taken by Simon Tang with the Coronado SolarMax II 90 Double Stack BF15

    Featuring the sunspot AR2706.

  • Cassiopea A recorded with SPIDER radio telescope

    Cassiopeia A is a very important supernova remnant for radio astronomy since it's the brightest extrasolar radio source in the sky when studying at frequencies above 1 GHz. This feature makes it a conquest within the reach of radio telescopes equipped with not huge antennas, but it is still a relatively weak radio source. In fact, having a flux of around 2400 Jansky at a frequency of 1,42 GHz, it's a lot weaker than the Sun that is around 40000 Jansky! In this article we will see how to use SPIDER radio telescope and its RadioUniversePRO software to record the signal from Cassiopea A by aligning the antenna, removing the artificial signals and recording transists, spectra and radio maps.

     

     

    Cassiopeia A (purple line) is the most powerful extra Solar System source but it's still very weak!

     

    In visible frequencies, Cassiopeia A is extremely weak since the interstellar dust of the Milky Way plane absorbs the visible radiation. Cassiopeia A (also called Cas A) was identified in 1947 (one of the first radio sources to be identified) while its optical counterpart was discovered in 1950. It's thought that supernova that created Cassiopeia A exploded about 11,000 years ago and that the light of the explosion reached Earth about 300 years ago. We have no infos of a sighting of this supernova, it is possible that the sixth magnitude star 3 Cassiopeiae, that John Flamsteed cataloged by August 16, 1680, was actually Cas A.

     

    Cassiopea A supernova remnant across the spectrum: Gamma rays (magenta), X-rays (blue, green), visible light (yellow), infrared (red) and radio (orange). Credits: NASA/DOE/Fermi LAT Collaboration, CXC/SAO/JPL-Caltech/Steward/O. Krause et al., and NRAO/AUI

     

    Thanks to the high sensitivity of SPIDER radio telescope's H142-One receiver, it is possible to record radio signals coming also from objects outside the Solar System. Then we used the advanced features of SPIDER and RadioUniversePRO software to record the incoming signal from Cassiopea A during the day and in the presence of clouds. Having to aim for a weak radio source, we must first of all be sure that the radio telescope is correctly aimed to the right sky area: so we used the Offset Alignment feature of RadioUniversePRO to perform a precision alignment on the Sun that, being a very strong radio source, it's perfect to align the mount of the SPIDER radio telescope.

     

    Cassiopea A recorded with SPIDER radio telescope: automatic alignment with RadioUniversePRO

     

     

    We then used the Source Visibilities tab of RadioUniversePRO (where the radio source database is included) to verify that Cassiopeia A had a good elevation from the ground (it is in fact recommended to aim high objects least 30 degrees from the ground) and then to precisely point this radio source. Before starting to record data, we verified the presence of interferences in the frequency band (50 MHz, centered at 1420 MHz) recorded by the SPIDER radio telescope. As you can see in the image below, the hydrogen line at 1420 MHz is clearly visible along with some artificial interferences but we can easily isolate it thanks to the BBC Tools tool of RadioUniversePRO. This way the SPIDER radio telescope will not record artificial radio signals.

     

    Cassiopea A recorded with SPIDER radio telescope: Hydrogen line and artificial interferences

     

    We have therefore captured a Cross-Scan, a technique that involves recording a transit in both Elevation and Azimuth (or even in Right Ascension and Declination), centered on the object. This way we get a graph of the intensity of the radio emission along a cross centered on the object and that allows to determine the maximum radio emission of Cassiopeia A. In order to perform this operation, we select the "TPI Plot" tab in RadioUniversePRO and we use the Cross-Scan feature, we select the length of the scan, the separation of each record point and the integration time of each record point. The SPIDER radio telescope mount moves the antenna and the software creates a graph like the one you can see in the image below.

    Cassiopea A recorded with SPIDER radio telescope: Cross-Scan record of Cassiopea A

     

    RadioUniversePRO saves the data in various formats that can then be processed with different softwares. In this case we used a simple editor to generate a graph that shows both transits 15 degrees long with the variation of the radiometric datum recorded both in elevation and azimuth. We clearly notice the increase in the recorded radio value caused by Cassiopea A. In this way we also verified that the SPIDER radio telescope mount is perfectly aligned on the radio sources in the sky and that Cassiopea A was perfectly aimed.

    Cassiopea A recorded with SPIDER radio telescope: Cross-Scan graph of Cassiopea A

     

    So we recorded the calibrated spectrum of Cassiopea A in order to to highlight the emission line of neutral hydrogen at 1420 MHz. For this operation we used the On-Off feature of RadioUniversePRO with spectrum recording: by recording data from the source radio ("on" position) and then calibrating it to a point in the sky away from the radio source ("off" position), the result is a calibrated spectrum. The result is visible in the image below, you can see how the SPIDER radio telescope has perfectly highlighted the emission of the hydrogen line at 1420 MHz.

     

    Cassiopea A recorded with SPIDER radio telescope: calibrated spectrum with hydrogen line

     

    We then performed a capture sequence of radio maps in the same area of Cassiopea A, using the Mapping function of RadioUniversePRO. We have set the capture of an area of 15x15 degrees, with 30 seconds of integration for each point and a separation between the points of 1 degree. In order to check the consistency of the recordings we recorded different maps at different times and, as you can see in the image below, all of them show an increase in the signal right close to the map center, just where you expect to find Cassiopea A.

    Cassiopea A recorded with SPIDER radio telescope: two Cassiopea A radio maps show signal increase just close to the map center

     

    By saving recorded data in FITS format (just like the professional radio telescopes) we have therefore extracted the data that can be processed with different softwares. Then we used the NASA FITS Viewer software to process one of the radio maps, better highlighting Cassiopea A signal from the sky background. The radio map captured by the SPIDER was then compared to an optical image, as you can see in the image below. It is easy to see how, in an area apparently empty of particular objects, the SPIDER radio telescope instead records an important object, just the supernova remnant known as Cassiopea A in the nomenclature used for radio sources.

     

    Cassiopea A recorded with SPIDER radio telescope: Cassiopea A sky area optical and radio image comparison

     

    SPIDER is the first radio telescope that has been specifically developed and designed by PrimaLuceLab in order to allow everyone to discover the magic of real radio astronomy without the need of being a radio astronomer to make it work! Click here to discover the full line of SPIDER radio telescopes.

  • NexDome Setup by Frank Parks in San Diego

    Here is my NexDome in San Diego being prepared for the FSQ-106 imaging system.  The 8-foot NexDome was quite easy to assemble and is well made for a very affordable dome.  My next project is to cut down some more trees and start narrowband imaging.  Thanks for the great service.
    — Frank

  • Images taken with Comet Hunter and ASI1600MM-Cooled Camera

    These images where taken using the Comet Hunter. The camera is an ZWO ASI1600mm-Cool.

  • Photos taken by Alex Roberts with Explore Scientific FCD100 127ED Refractor

    Photos taken by Alex Roberts with FCD100 127ED Telescope.

    https://alexroberts.smugmug.com/Alex-Roberts-Astrophotos/

  • 2017 Totality of Eclipse by Bryan Cogdell

    Here is one of the images I captured during totality on Monday. As the Moon moved eastward it revealed more prominences with amazing detail - I could actually see this through binoculars! And the magnetic interaction on the corona was astounding. This particular shot was taken with an older (Japanese made) Vixen 114ED f/5.3 refractor and Canon 70D.

  • Bubble Nebula by Bob Finnigan

    Tim Stone And Bob Finnigan

    This is Tim’s rendering 10 ten min Ha, 11 OIII and 18 SII  all at bin2 take with the 17 inch PlaneWave and the Apogee 16u camera at -30c Paramont ME Mount  and a Moag with a SBIG STi. guider 

    Oct 31,2012 thru Nov 4, 2012

     

     

    Sep 20. 2017 by Tim with the 20 inch and the AO

  • Eclipse Images by Dennis Beatty

    "I shot about 400 images that morning and I am so pleased with
    them. This was my first attempt doing anything like this. I used a Canon
    5D camera with a 10 inch Meade LX-200. I live in southern Oregon and we had
    about 94% totality. I love the sunspots in the third image."

    Dennis Beatty

  • Calcium K Image of Sun by Mike Taormina

    HI Farah,

    I just submitted a positive review to your website for the Lunt Calcium-K B1800 blocker diagonal I purchased from you last week. I had a chance to image with yesterday and was able to capture a very nice Calcium-K image.

    MikeTaormina_LuntB1800_CaK

  • Sun Image taken by Harvey Brubacker

    This weekend was a bust for any imaging, but I did find some lost solar

    images from two weekends ago.

    Here's my favorite from the bunch.

    Inverted image, color tinted gold.

    Taken with a Lunt solar 60mm pressure tuned scope, double stacked with 50mm
    element.

    Camera was the Canon 60Da, ISO 100 at 1/40 sec.

     

    Harvey Brubacker

    harvey_brubacker_solar_image

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