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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"

2623 results found.

  1. GRB 171010A: possible SN component
  2. IceCube-171106A - IceCube observation of a high-energy neutrino candidate
  3. GRB 171030A: MASTER inspection of the IPN error box of the short GRB.
  4. GRB 171103A: Fermi GBM observation
  5. GRB 171010A: VLT spectroscopic identification of the associated SN 2017htp
  6. GRB 171030A: IPN error box through NSs probability merging rate map
  7. Swift trigger 781740: Further analysis from Swift and Fermi/GBM
  8. Fermi-GBM Detection of possible burst from AXP CXOU J164710.2-455216/PSR J1647-4552
  9. Swift trigger 779171 is probably a noise fluctuation
  10. IceCube-171015A - IceCube observation of a high-energy neutrino candidate event
  11. BAT trigger 778435 is not a GRB.
  12. GRB 171013A: Swift detection of a possible burst
  13. GRB 171010A: Swift/UVOT Detection
  14. GRB 171010A: ePESSTO NTT spectroscopic redshift
  15. GRB 171010A: OT, spectrum, and possible host galaxy
  16. LIGO/Virgo G298048: Mid-Infrared Spitzer/IRAC Observations at 3.6 and 4.5 microns
  17. Swift Trigger 775946 is a Galactic transient, not GRB 171003
  18. GRB 171003A: LT early optical observations
  19. GRB 170906C: 15 GHz upper limits from AMI
  20. LIGO/Virgo G298048: Summary of Pi of the Sky observations
  21. IceCube-170922A - IceCube observation of a high-energy neutrino candidate event
  22. LIGO/Virgo G298048: SRT observations of SSS17a in NGC 4993
  23. LIGO/Virgo G299232: Lulin Observations of Possible OTs
  24. LIGO/VIRGO G298048: Radio detection of SSS17a at 6 GHz with the VLA
  25. GRB 170902A: Swift detection of a burst or possible Galactic transient
  26. LIGO/Virgo G298048
  27. LIGO/Virgo G298048: Possible Plateau in Ks band revealed by continued Gemini-South observations
  28. LIGO/Virgo G299232: HAWC follow-up
  29. LIGO/Virgo G298048: Zadko Telescope 7 day observations of the OT candidate SSS17a/DLT17ck
  30. GRB 170827A: Swift-XRT refined Analysis
  31. LIGO/Virgo G299232: OVRO-LWA simultaneous low frequency radio observations of localization region
  32. LIGO/Virgo G299232/PGWB170825.55: MASTER Global-Net OT inside NGC1343 discovery
  33. LIGO/Virgo G299232 : Fermi-LAT search for high-energy gamma-ray counterpart
  34. LIGO/Virgo G298389: HAWC follow-up
  35. LIGO/Virgo G299232: AGILE MCAL detection of a short gamma-ray candidate
  36. LIGO/Virgo G297595: INTEGRAL pointed follow-up observations
  37. LIGO/Virgo G298048: MASTER Global-Net early optical observations and the Possible KiloNova SSS17a in NGC 4993 photometry and merging rate
  38. LIGO/Virgo G298048: HAWC follow-up
  39. LIGO/Virgo G298048: H.E.S.S. very-high energy gamma-ray follow-up
  40. LIGO/Virgo G298048: INTEGRAL pointed follow-up observations
  41. LIGO/Virgo G298936 : Fermi-LAT search for a high-energy gamma-ray counterpart
  42. LIGO/Virgo G298048: Continued VLA monitoring at 6 GHz
  43. LIGO/Virgo G298936: Identification of a GW Binary Black Hole Candidate
  44. LIGO/Virgo G298048: Global properties and star-formation rate of NGC 4993
  45. LIGO/Virgo G298048: observations of optical counterpart candidate with CHILESCOPE observatory
  46. LIGO/Virgo G298048: ASKAP observations of SSS17a and NGC 4993 at 1.345 GHz
  47. LIGO/Virgo G298048: Gemini-South Near-Infrared Spectroscopy
  48. LIGO/Virgo G298048: VLA observation at 15 GHz
  49. LIGO/Virgo G298048: observations of optical counterpart candidate with CHILESCOPE observatory
  50. LIGO/Virgo G298048: Zadko observations of the OT candidate SSS17a/DLT17ck
  51. LIGO/Virgo G298048: NuSTAR limits on X-ray emission
  52. LIGO/Virgo G298048: ASKAP follow up
  53. LIGO/Virgo G298048: Kanata/HONIR NIR photometry of the possible counterpart of G298048
  54. LIGO/Virgo G298389 : Fermi-LAT search for a high-energy gamma-ray counterpart
  55. LIGO/Virgo G298048: VLA observation at 6 GHz
  56. LIGO/Virgo G298048: Continued VLA observations
  57. LIGO/Virgo G298048: Possible X-ray detection with Swift
  58. LIGO/Virgo G298048: VLBA observations of the possible counterpart SSS17a in NGC 4993
  59. LIGO/Virgo G298048: Possible features in the spectrum of GW counterpart SSS17a
  60. LIGO/Virgo G298048: Rapid Evolution of Possible Counterpart
  61. LIGO/Virgo G298048: Observed fading of optical counterpart SSS17a
  62. LIGO/Virgo G298048: Continued observation for DLT17ck
  63. LIGO/Virgo G298048: Brightening of Possible Counterpart
  64. LIGO/Virgo G298048: Subaru HSC z-band photometry of the possible optical counterpart
  65. LIGO/Virgo G298048: Likelihood of SSS17a Being an Unrelated Extragalactic Transient in NGC 4993
  66. LIGO/Virgo G298048: REM optical/NIR observations
  67. LIGO/Virgo G298048: Pan-STARRS detections and izy photometry of the possible optical/NIR counterpart in NGC4993
  68. LIGO/Virgo G298048: Galaxy-Targeted Optical Followup With Las Cumbres Observatory
  69. LIGO/VIRGO G298048: The Potential Optical Counterpart in NGC 4993 Has Afterglow-Like Colors
  70. LIGO/Virgo G298048: Las Cumbres Observatory Detection of The Possible Optical Counterpart in NGC 4993
  71. LIGO/Virgo G298048: Inspection of archival HST data at the position of the potential optical counterpart
  72. LIGO/Virgo G298048 : Fermi-LAT search for a high-energy gamma-ray counterpart
  73. LIGO/Virgo G298048: correction to the luminosity distance reported in GCN 21509
  74. LIGO/Virgo G298048: Identification of a binary neutron star candidate coincident with Fermi GBM trigger 524666471/170817529
  75. LIGO/Virgo G298048: Fermi GBM trigger 524666471/170817529: LIGO/Virgo Identification of a possible gravitational-wave counterpart
  76. LIGO/Virgo G297595: REM optical/NIR observations
  77. LIGO/Virgo G297595: Pan-STARRS coverage and transients over the first 5hrs
  78. LIGO/Virgo G297595 : Fermi-LAT search for high-energy gamma-ray counterpart
  79. LIGO/Virgo G296853: MASTER SN detection near center error-area
  80. LIGO/Virgo G296853: no INTEGRAL data at the time of the event
  81. LIGO/Virgo G296853: Fermi-LAT search for high-energy gamma-ray counterpart
  82. GRB170730A detecetd by INTEGRAL. Refined analysis
  83. IBAS weak Alert nr.7881: possible GRB 170730A
  84. GRB 170714A: z-band afterglow candidate for OSIRIS/GTC
  85. Fermi GBM Detection of possible burst from AXP 4U 0142+61
  86. GRB 170710B: Swift-XRT and UVOT observations
  87. GRB 170710A: Gemini-S candidate counterpart
  88. GRB 170626A: SAO RAS possible OT detection
  89. LIGO/Virgo G288732: Pan-STARRS coverage of the Fermi/LAT candidate position
  90. LIGO/Virgo G288732: VLA imaging of the possible Fermi/LAT counterpart
  91. LIGO/Virgo G288732: Kiso/KWFC optical imaging of the possible Fermi/LAT counterpart
  92. LIGO/Virgo G288732: HAWC follow-up
  93. LIGO/Virgo G288732: Swift/UVOT follow up of the possible LAT counterpart
  94. LIGO/Virgo G288732: Swift-XRT follow up of the putative LAT counterpart
  95. LIGO/Virgo G288732: INTEGRAL search for a prompt gamma-ray counterpart
  96. LIGO/Virgo G288732: Fermi-LAT detection of a weak candidate
  97. GRB 170607A: Correction on the possible host galaxy identification
  98. Swift Trigger 755873: D50 optical limits
  99. Swift Trigger 755873: a possible GRB
  100. GRB 170531B: Swift/UVOT Detection

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