Astro Photos

  • Taurus A "discovered" by SPIDER radio telescope

    This entry was posted on May 2, 2018 by Filippo Bradaschia.

    Taurus A "discovered" by SPIDER radio telescope
    Taurus A is the radio source in Taurus constellation that corresponds to the Crab Nebula (M1), the supernova remnant exploded on July 4, 1054 and noted by Chinese and Arabian astronomers of the time. Since then, the gas cloud has expanded and today is over 6 light years large. In this article we see how the SPIDER radio telescope "discovered" it by capturing the radio waves emitted by Taurus A and converting them into a radio map, a real photograph in radio waves of this nebula. In fact it is believed that Taurus A emits radio waves for synchrotron radiation caused by electrons in fast spiral motions around magnetic field lines generated by the pulsar inside it. Thanks to the large antenna and the 1420 MHz H142-One receiver, the SPIDER radio telescope was able to easily record the weak signal and, thanks to the precise mount and pointing system, it generated a radio map with the same technique used by professional radio telescopes.
    Studying the sky at the frequency of 1420 MHz has several advantages including the ability to capture radio waves even during the day and through the clouds. But at this frequency the electromagnetic emission of many radio sources is quite weak (in fact, professional radio telescopes use very large antennas and are very expensive). At the frequency of 1420 MHz the strongest radio sources are:

    Sole: flux about 40000 Jansky
    Cassiopea A: flux about 2400 Jansky
    Centaurus A: flux about 1700 Jansky
    Cygnus A: flux about 1600 Jansky
    Sagittarius A: flux about 1600 Jansky
    Vela X: flux about 1600 Jansky
    Taurus A (M1): flux about 875 Jansky
    Orion A (M42): flux about 520 Jansky
    NGC2237: flux about 260 Jansky

    With SPIDER, the Sun is so strong we can use it as reference radio source to align the mount on the fly. All the other radio sources are weaker but the high sensitivity of the SPIDER radio telescope allow you to really record them. In order to verify this, we used the SPIDER 300A radio telescope installed in Marcello Ceccarelli visitor center in Medicina (Bologna, Italy - near the professional radio telescopes of INAF) to record a radio map of Taurus A and demonstrating the features of RadioUniversePRO control software that comes with the SPIDER radio telescope.

    A radio telescope is different from an optical telescope by many aspects: one of these is that it collects radio waves from a single area in the sky. Just to give an example, it's like having a telescope with a CCD camera that comes with a single large pixel. In order to create radio maps, technique consists in moving the antenna with small movements and, for every sky position, record radio waves coming from space tracking the sky apparent movement. Then the SPIDER antenna is moved to a new position and record the next pixel value. For every pixel, RadioUniversePRO software calculates the total amount of radio waves captured and displays this value with a color based on a color scale chosen by the user.

    RadioUniversePRO software allows you to point the radio telescope to the precise sky position of the radio source, visualize in real time the bandwidth spectrum in frequency so you can see if you have artificial signal in it (allowing you to filter these from your recordings) and define radio map specifications like:

    Dimensions in degrees (AR e DEC)
    Pixel separation
    Integration time for every pixel
    Colour scale type for visualization
    Hystogram stretching
    Optional visualization with level curves

    So we started a 3 hours capture, setting the following parameters in RadioUniversePRO:

    Map dimensions: 15 x 15 degrees
    Pixel separation: 0,4 degrees
    Integration time for every pixel: 5 seconds
    The result is the map that we show in the image below. You can easily see the increase of the signal at the center of the map, corresponding to Taurus A position. The increase in the visible signal at the top right of the image is the Milky Way, in fact Taurus A does not lie perfectly on the plane of our galaxy but it is a few degrees away (as confirmed by the radio map). The image below shows the same radio map but displayed with the level curves.

     

    This way we demonstrated that, thanks to the high sensitivity and pointing precision of the SPIDER radio telescope, it is possible to realize radio maps also of weak radio sources using the same techniques employed by professional radio telescopes!

  • Eagle Nebula

    QHY183M, Exp Sci ED127, 0.7x reducer, CGE Pro, Rayox Saddle
    Ha 6h (combined with a customers data)
    SII 1h 30m
    OIIII 1h 30m
  • M51 Galaxy By Dan Yagi

     

    Taken by Dan Yagi

    ZWO 1600 Monochrome

  • Tim Connolly - Elephant Trunk Nebula

    Customer Tim Connolly captured these gorgeous images of the concentrated region of gases known as the Elephant Trunk Nebula within the ionized gas region IC 1396.
    I finally have been using my new monochrome camera and filters!
    Elephant’s Trunk Nebula - IC1396, in the constellation Cepheus. The first image is constructed using the Hubble Palette. (Red Channel - Sulphur II, Green - Hydrogen Alpha, Blue - Oxygen III). The second image is a bi-color image using Hydrogen Alpha (Red) and Oxygen III (Blue/Green).
    Lights - 12 - 5 minute exposed images
    Darks - 25
    Bias - 25
    Flats - 25
    Orion 8” F3.9 Newtonian
    ZWO ASI 1600 mm-pro
    ZWO 7nm narrowband filters
    Celestron CGEM DX Mount
    Captured using SGPro (Trial Version)
    Stacked in DSS
    Processed in Photoshop
    Tim Connolly ??
  • 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.

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