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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"

22077 results found.

  1. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  2. EP240919a / GRB 240919A: SVOM/VT upper limit
  3. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  4. EP240918b and EP240918c: EP-FXT follow-up observations
  5. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  6. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  7. LIGO/Virgo S240919bn: GOTO optical upper limits
  8. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  9. EP240919a: EP-FXT follow-up observation update
  10. EP240913a/GRB 240913C: 1.6m Mephisto observations
  11. EP240918a: SVOM/VT upper limit
  12. EP240919a / GRB 240919A: REM optical and NIR upper limits
  13. EP240918b and EP240918c: Optical upper limits with Kinder observations
  14. GRB 240414A: further radio observations with the VLA
  15. EP240919a: Optical upper limit with Kinder observations
  16. GRB 240919A / EP240919a: SVOM/GRM observation
  17. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  18. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  19. EP EP240919a: Global MASTER-Net observations report
  20. GRB 240910A: radio detection with the VLA
  21. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  22. EP240919a: NOT and Gemini optical observations
  23. EP240919a: GOTO optical upper limits
  24. EP240919a: JinShan optical upper limits
  25. EP240919a is likely a GRB event
  26. EP240919a: EP-WXT detection of a fast X-ray transient
  27. GRB 240918A and GRB 240918B : INTEGRAL SPI ACS LIGHT CURVE
  28. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  29. EP240918a: EP observation update
  30. GRB 240910A: further Swift observations and confirmation of afterglow
  31. Fermi GRB 240918A: Global MASTER-Net observations report
  32. EP EP240918a: Global MASTER-Net observations report
  33. EP240918a: JinShan optical upper limits
  34. EP240918a: Optical upper limits with Kinder observations
  35. EP240918a: an X-ray transient detected by Einstein Probe
  36. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  37. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  38. GRB 240821A: radio observation with the VLA
  39. GRB 240916A: Swift-XRT afterglow detection
  40. GRB 240916A: Swift ToO observations
  41. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  42. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  43. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  44. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  45. EP EP240913a: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  47. GRB 240916A INTEGRAL SPI ACS LIGHT CURVE
  48. EP240913a: VLT/HAWK-I near-infrared upper limits
  49. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  50. GRB 240914A: Swift-XRT observations
  51. GRB 240910A: SVOM/VT optical observations
  52. GRB 240914A: Swift ToO observations
  53. EP240913a: NOT optical upper limits
  54. EP240913a: JinShan optical upper limits
  55. EP240913a: ESO-NTT optical observations
  56. GRB 240914A: ESO-NTT optical observations
  57. GRB 240905E: further NOT optical observations
  58. EP240913a: A GRB Event
  59. EP240913a: EP-WXT detection of a fast X-ray transient
  60. GRB 240911A: LCO optical observations
  61. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  62. GRB 240912A: Swift/UVOT Detection
  63. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  64. Fermi trigger No 747920561: Global MASTER-Net observations report
  65. GRB 240911A: Swift-XRT observations
  66. Fermi GRB 240913A: Global MASTER-Net observations report
  67. GRB 240912A: J-band observations with WINTER
  68. Swift GRB 240912A: Global MASTER-Net observations report
  69. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  70. GRB 240911A: Tiled Swift observations
  71. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  72. GRB 240912A: Redshift from OSIRIS+/GTC
  73. Fast X-ray Transient EP240801a: GMRT radio observations
  74. GRB 240910A: NOT optical observations
  75. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  76. GRB 240910A: JinShan optical observations
  77. GRB 240910A: GOTO candidate optical counterpart
  78. EP240908a: Optical afterglow confirmation
  79. GRB 240910A: Swift ToO observations
  80. GRB 240825A: 7DT Optical Upper Limit
  81. GRB 240905E: SVOM/VT optical observations
  82. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  83. LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
  84. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  85. EP240908a: Mondy and AbAO follow-up observations
  86. EP240908a: Updates on the WXT detection result around the trigger time
  87. Fermi GRB 240910A: Global MASTER-Net observations report
  88. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  89. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  90. EP240908a: optical afterglow candidate
  91. EP EP240908a: Global MASTER-Net observations report
  92. Fermi trigger No 747553301: Global MASTER-Net observations report
  93. EP240908a: TRT optical upper limit
  94. GRB 240905B: GOTO optical upper limits
  95. EP240908a: EP detection of a fast X-ray transient
  96. Fermi GRB 240908A: Global MASTER-Net observations report
  97. GRB 240905E: GIT optical upper limit
  98. GRB 240905B: Swift-XRT observations
  99. GRB 240905E: Gaoyazi/GOT optical upper limits
  100. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits

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