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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"

22076 results found.

  1. EP240919a / GRB 240919A: SVOM/VT upper limit
  2. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  3. EP240918b and EP240918c: EP-FXT follow-up observations
  4. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  5. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  6. LIGO/Virgo S240919bn: GOTO optical upper limits
  7. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  8. EP240919a: EP-FXT follow-up observation update
  9. EP240913a/GRB 240913C: 1.6m Mephisto observations
  10. EP240918a: SVOM/VT upper limit
  11. EP240919a / GRB 240919A: REM optical and NIR upper limits
  12. EP240918b and EP240918c: Optical upper limits with Kinder observations
  13. GRB 240414A: further radio observations with the VLA
  14. EP240919a: Optical upper limit with Kinder observations
  15. GRB 240919A / EP240919a: SVOM/GRM observation
  16. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  17. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  18. EP EP240919a: Global MASTER-Net observations report
  19. GRB 240910A: radio detection with the VLA
  20. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  21. EP240919a: NOT and Gemini optical observations
  22. EP240919a: GOTO optical upper limits
  23. EP240919a: JinShan optical upper limits
  24. EP240919a is likely a GRB event
  25. EP240919a: EP-WXT detection of a fast X-ray transient
  26. GRB 240918A and GRB 240918B : INTEGRAL SPI ACS LIGHT CURVE
  27. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  28. EP240918a: EP observation update
  29. GRB 240910A: further Swift observations and confirmation of afterglow
  30. Fermi GRB 240918A: Global MASTER-Net observations report
  31. EP EP240918a: Global MASTER-Net observations report
  32. EP240918a: JinShan optical upper limits
  33. EP240918a: Optical upper limits with Kinder observations
  34. EP240918a: an X-ray transient detected by Einstein Probe
  35. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  36. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  37. GRB 240821A: radio observation with the VLA
  38. GRB 240916A: Swift-XRT afterglow detection
  39. GRB 240916A: Swift ToO observations
  40. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  41. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  42. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  43. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  44. EP EP240913a: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  46. GRB 240916A INTEGRAL SPI ACS LIGHT CURVE
  47. EP240913a: VLT/HAWK-I near-infrared upper limits
  48. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  49. GRB 240914A: Swift-XRT observations
  50. GRB 240910A: SVOM/VT optical observations
  51. GRB 240914A: Swift ToO observations
  52. EP240913a: NOT optical upper limits
  53. EP240913a: JinShan optical upper limits
  54. EP240913a: ESO-NTT optical observations
  55. GRB 240914A: ESO-NTT optical observations
  56. GRB 240905E: further NOT optical observations
  57. EP240913a: A GRB Event
  58. EP240913a: EP-WXT detection of a fast X-ray transient
  59. GRB 240911A: LCO optical observations
  60. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  61. GRB 240912A: Swift/UVOT Detection
  62. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  63. Fermi trigger No 747920561: Global MASTER-Net observations report
  64. GRB 240911A: Swift-XRT observations
  65. Fermi GRB 240913A: Global MASTER-Net observations report
  66. GRB 240912A: J-band observations with WINTER
  67. Swift GRB 240912A: Global MASTER-Net observations report
  68. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  69. GRB 240911A: Tiled Swift observations
  70. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  71. GRB 240912A: Redshift from OSIRIS+/GTC
  72. Fast X-ray Transient EP240801a: GMRT radio observations
  73. GRB 240910A: NOT optical observations
  74. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  75. GRB 240910A: JinShan optical observations
  76. GRB 240910A: GOTO candidate optical counterpart
  77. EP240908a: Optical afterglow confirmation
  78. GRB 240910A: Swift ToO observations
  79. GRB 240825A: 7DT Optical Upper Limit
  80. GRB 240905E: SVOM/VT optical observations
  81. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  82. LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
  83. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  84. EP240908a: Mondy and AbAO follow-up observations
  85. EP240908a: Updates on the WXT detection result around the trigger time
  86. Fermi GRB 240910A: Global MASTER-Net observations report
  87. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  88. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  89. EP240908a: optical afterglow candidate
  90. EP EP240908a: Global MASTER-Net observations report
  91. Fermi trigger No 747553301: Global MASTER-Net observations report
  92. EP240908a: TRT optical upper limit
  93. GRB 240905B: GOTO optical upper limits
  94. EP240908a: EP detection of a fast X-ray transient
  95. Fermi GRB 240908A: Global MASTER-Net observations report
  96. GRB 240905E: GIT optical upper limit
  97. GRB 240905B: Swift-XRT observations
  98. GRB 240905E: Gaoyazi/GOT optical upper limits
  99. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  100. GRB 240905B: Swift ToO observations

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