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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

4057 results found.

  1. LIGO/Virgo G298048: Possible Plateau in Ks band revealed by continued Gemini-South observations
  2. LIGO/Virgo G298048: Continued Gemini South observations
  3. LIGO/Virgo G299232: GRAWITA Asiago optical observations
  4. LIGO/Virgo G299232: continued WHT observations of the field of SwiftJ014008.5+343403.6
  5. LIGO/Virgo G298936: PIRATE observations
  6. LIGO/Virgo G299232 ANTARES search (2)
  7. LIGO/Virgo G298048: GMRT Follow-up of SSS17a at 1.4 GHz
  8. LIGO/Virgo G299232: GRAWITA Campo Imperatore optical observations
  9. LIGO/Virgo G298048: Discovery of X-ray emission from SSS17a in NGC4993
  10. LIGO/Virgo G298048: European VLBI Network (EVN) upper limit on 5 GHz compact emission from SSS17a
  11. LIGO/Virgo G299232: SVOM/2.16-m Optical Telescope Observations of Swift UVOT Transient
  12. LIGO/Virgo G298048: OVRO 40m telescope follow-up
  13. LIGO/Virgo G299232: HAWC follow-up
  14. LIGO/Virgo G299232: Further Swift/UVOT Observations of Optical Transient SwiftJ014008.5+343403.6
  15. LIGO/Virgo G299232 : RATIR Optical and NIR Observations of Swift UVOT source
  16. LIGO/Virgo G299232: WHT non-detection u-band optical transient
  17. LIGO/Virgo G299232: Liverpool Telescope observations
  18. LIGO/Virgo G299232: observations of the optical Transient Discovered by Swift/UVOT
  19. LIGO/Virgo G299232: PIRATE observations of MASTER OT J033744.97+723159.0
  20. LIGO/Virgo G298936: Updated localization from parameter estimation on LIGO and Virgo data
  21. LIGO/Virgo G298048: ALMA upper limits on 98 GHz emission from SSS17a
  22. LIGO/Virgo G299232/PGWB170825.55: early MASTER observations of the Swift UVOT source position
  23. LIGO/Virgo G296853: PIRATE observations
  24. LIGO/Virgo G298048: ALMA observations
  25. LIGO/Virgo G298048: Konus-Wind observations
  26. LIGO/Virgo G299232: GRAWITA Asiago/Copernico Telescope observations
  27. LIGO/Virgo G298048: Zadko Telescope 7 day observations of the OT candidate SSS17a/DLT17ck
  28. LIGO/Virgo G299232: COATLI Observations of MASTER OT J033744.97+723159.0
  29. LIGO/Virgo G299232 : MAXI/GSC observations
  30. LIGO/Virgo G298048: Further ATCA follow-up of SSS17a in NGC 4993
  31. LIGO/Virgo G299232: Continued observation of the transient near NGC 1343
  32. LIGO/Virgo G299232: WHT spectrum of MASTER OT J033744.97+723159.0
  33. LIGO/Virgo G299232/PGWB170825.55: MASTER OT J033744.97+723159.0 inside 25m isophota of the NGC1343 galaxy is reddening
  34. IPN Triangulation of GRB 170827B (short)
  35. LIGO/Virgo G299232: Optical Transient Discovery by Swift/UVOT
  36. LIGO/Virgo G298936: HAWC follow-up
  37. LIGO/Virgo G299232 TZAC/TAROT observations
  38. LIGO/Virgo G299232: OVRO-LWA simultaneous low frequency radio observations of localization region
  39. LIGO/Virgo G299232: LOFAR follow-up
  40. LIGO/Virgo G299232: Transient near NGC 1343 has a somewhat blue r-i color
  41. LIGO/Virgo G299232/PGWB170825.55: MASTER OTJ033744.97+723159.0 off set from NGC1343 galaxy
  42. LIGO/Virgo G299232/PGWB170825.55: MASTER Global-Net OT inside NGC1343 discovery
  43. LIGO/Virgo G299232: CALET Observations
  44. LIGO/Virgo G298936: Astrosat CZTI upper limits
  45. LIGO/Virgo G299232: XRT Rank 2 source is not real
  46. LIGO/Virgo G299232: Astrosat CZTI upper limits
  47. LIGO/VIRGO G299232: Fermi GBM Observations
  48. LIGO/Virgo G299232 : Fermi-LAT search for high-energy gamma-ray counterpart
  49. LIGO/Virgo G298389: HAWC follow-up
  50. LIGO/Virgo G298048: uGMRT Follow-up of SSS17a at 400 MHz and 1.4 GHz
  51. LIGO/Virgo G299232: Nearby Galaxies in the Localization Volume
  52. LIGO/Virgo G298936: CALET Observations
  53. LIGO/Virgo G299232: Swift/BAT data search
  54. LIGO/VIRGO G298048: INAF VST-ESO PARANAL observations of NGC4993
  55. LIGO/Virgo G299232: AGILE GRID observations
  56. LIGO/Virgo G299232: AGILE MCAL detection of a short gamma-ray candidate
  57. LIGO/Virgo G299232: INTEGRAL search for a prompt gamma-ray counterpart
  58. LIGO/Virgo G299232: COINCIDENT IceCube neutrino observation UPDATE
  59. LIGO/Virgo G296853: VLT observations by GLGW Hunters
  60. LIGO/Virgo G299232 ANTARES search
  61. LIGO/Virgo G297595: INTEGRAL pointed follow-up observations
  62. LIGO/Virgo G299232: FOUND COINCIDENT IceCube neutrino observation
  63. LIGO/Virgo G299232: Identification of a GW Compact Binary Coalescence Candidate
  64. LIGO/Virgo G297595: Gemini and VLT observations by GLGW Hunters
  65. LIGO/Virgo G298936: Liverpool Telescope Spectoscopy of GWFUNC-17ure
  66. LIGO/Virgo G298936 TAROT/TZAC observations
  67. LIGO/Virgo G298936 : MAXI/GSC observations
  68. LIGO/Virgo G298048: MASTER Global-Net early optical observations and the Possible KiloNova SSS17a in NGC 4993 photometry and merging rate
  69. LIGO/Virgo G298048: Pierre Auger Observatory neutrino follow-up
  70. LIGO/Virgo G298048: Subaru HSC z-band imaging of the OT candidate SSS17a
  71. LIGO/Virgo G298048: Near-infrared fading from Gemini-South
  72. LIGO/Virgo G298048: HAWC follow-up
  73. LIGO/Virgo G298048: Gemini-South Imaging and Spectroscopy
  74. LIGO/Virgo G298048: MUSE Integral Field Observations
  75. LIGO/Virgo G298048: LWA radio observations
  76. LIGO/VIRGO G298048: AAT/AAO spectroscopic observations of the GW counterpart candidate SSS17a/DLT17ck
  77. LIGO/Virgo G298048: LOFAR follow-up
  78. LIGO/Virgo G298936: GWFUNC/CNEOST optical observations and an optical transient
  79. LIGO/Virgo G298048: H.E.S.S. very-high energy gamma-ray follow-up
  80. LIGO/Virgo G297595: H.E.S.S. very-high energy gamma-ray follow-up
  81. LIGO/Virgo G298048: INTEGRAL pointed follow-up observations
  82. LIGO/Virgo G298048: Results of the ASKAP search for fast radio bursts
  83. LIGO/Virgo G298048: ATCA follow-up of SSS17a in NGC 4993
  84. LIGO/Virgo G298048: Properties of NGC 4993
  85. LIGO/Virgo G298389: CALET Observations
  86. LIGO/Virgo G298936 : Fermi-LAT search for a high-energy gamma-ray counterpart
  87. LIGO/Virgo G298936: Swift/BAT data search
  88. LIGO/Virgo G298048: Continued VLA monitoring at 6 GHz
  89. LIGO/VIRGO G298936: Fermi GBM Observations
  90. LIGO/Virgo G298936: AGILE GRID observations
  91. LIGO/Virgo G298936: Updated localization from gravitational-wave data
  92. LIGO/Virgo G298936: AGILE MCAL observations
  93. LIGO/Virgo G298936 ANTARES search
  94. LIGO/Virgo G298936: INTEGRAL was inactive at the time of the event
  95. LIGO/Virgo G298936: IceCube neutrino observations
  96. LIGO/Virgo G298936: Identification of a GW Binary Black Hole Candidate
  97. LIGO/Virgo G298048: ESO/VLT optical observations
  98. LIGO/VIRGO G298048: VLA/JAGWAR observations of the CLU galaxies
  99. LIGO/Virgo G298048: Chandra X-ray observations
  100. LIGO/Virgo G298389 : MAXI/GSC observations

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