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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"

138 results found.

  1. GRB 250821A: Kilonova-Catcher optical upper limits
  2. GRB 250818B: Kilonova-Catcher optical afterglow detection
  3. GRB 250812A: Kilonova-Catcher optical afterglow detection
  4. GRB 250807B: Kilonova-Catcher optical afterglow detection
  5. GRB 250805A: Kilonova-Catcher optical upper limits
  6. GRB 250806A: Kilonova-Catcher optical upper limits
  7. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  8. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  9. GRB 250704A: GRANDMA observations
  10. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  11. GRB 250702F: GRANDMA observations
  12. GRB 250702F: Kilonova-Catcher optical afterglow detection
  13. GRB 250615A: Kilonova-Catcher optical upper limits
  14. GRB 250617B: Kilonova-Catcher optical afterglow detection
  15. GRB 250424A: Kilonova-Catcher optical afterglow detection
  16. GRB 250327B: Kilonova-Catcher Observations
  17. GRB 250322A: GRANDMA/TNOT optical upper limits
  18. GRB 250226A: GRANDMA Optical Observations
  19. GRB 250221A: GRANDMA/TAROT Detection
  20. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  21. GRANDMA/OPD observations of GRB250215A
  22. GRB 250129A: GRANDMA Continued Afterglow Detection
  23. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  24. GRB 250129A: COLIBRÍ Optical Observations
  25. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  26. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  27. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  28. GRB 241217A: GRANDMA/TAROT optical upperlimits
  29. GRB 241209B: GRANDMA/TRT upper limit
  30. GRB 241209D: COLIBRÍ detection of the afterglow
  31. GRB 241209A: COLIBRÍ Optical Upper Limit
  32. GRB 241209A: GRANDMA/TAROT upper limit
  33. GRB 241128A : RAPAS follow-up observations
  34. GRB 241113B : RAPAS follow-up observation
  35. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  36. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  37. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  38. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  39. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  40. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  41. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  42. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  43. GRB241030B: GRANDMA/TAROT Upper Limit
  44. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  45. GRB 241006A: VIRT Optical Upper Limit
  46. GRB 241009A: GRANDMA optical upper limits
  47. GRB 241006A: GRANDMA optical upper limits
  48. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  49. GRB 240828B: GRANDMA Optical Upper Limit
  50. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  51. GRB 240821A: Colibri Optical Upper Limit
  52. GRB 240821A: GMG Optical Upper Limit
  53. GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
  54. GRB 240809A : RAPAS follow-up observations
  55. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  56. GRB240715A: GRANDMA Optical Upper Limits
  57. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  58. EP240625a: GRANDMA Optical Upper Limits
  59. EP240618a: GRANDMA Optical Upper Limits
  60. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  61. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  62. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  63. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  64. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  65. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  66. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  67. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  68. X-ray transient EP240331a: Kinder optical upper limits
  69. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  70. IceCube-231211A: GRANDMA observations of PKS2047+098
  71. GRB231115A: GRANDMA Observations
  72. GRB 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
  73. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  74. GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
  75. GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
  76. GRB 230812B: GMG - GRANDMA observations
  77. LIGO/Virgo/KAGRA S230627c: GRANDMA observations of galaxies and ZTF counterpart candidates
  78. LIGO/Virgo/KAGRA S230615az: GRANDMA observations of GOTO and GIT candidates
  79. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  80. GRB 221110A: GRANDMA observations
  81. GRB 221009A: GRANDMA/Kilonova-Catcher observations
  82. GRB 221028A: GRANDMA observations
  83. GRB 221027B: GRANDMA observations
  84. GRB 221024A: GRANDMA observations
  85. GRB 221009A: SARA-RM 1m Optical Afterglow Detection
  86. GRB 221009A: GRANDMA observations
  87. GRB 220514A: GRANDMA Optical Afterglow Observations
  88. GRB 220427A: GRANDMA Early Optical Afterglow Detection
  89. GRB 220501A: GRANDMA/TJML Optical Observations
  90. GRB 220430A: GRANDMA observations
  91. GRB 220412A: GRANDMA observations
  92. GRB 220408A: GRANDMA observations
  93. GRB 220403B: GRANDMA observations
  94. GRB 220325A: GRANDMA observations
  95. GRB 220319A: GRANDMA observations
  96. GRB 210610B: T-CAT optical observations
  97. LIGO/Virgo S200316bj : No significant candidates in TAROT - FRAM - GRANDMA observations.
  98. LIGO/Virgo S200302c : No significant candidates in FRAM - TAROT - GRANDMA observations.
  99. LIGO/Virgo S200225q : No significant candidates in TAROT - FRAM - GRANDMA observations.
  100. LIGO/Virgo S200224ca : No significant candidates in TAROT - FRAM - GRANDMA observations

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