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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"

2959 results found.

  1. EP241126a: SVOM/VT observations
  2. The EP-WXT trigger 01709125191 is not a real source
  3. EP241126a: WFST Observations
  4. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345)
  5. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345).
  6. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  7. EP241126a: Optical Upper limits with Kinder observations
  8. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  9. EP241126a: EP-FXT follow-up observation update
  10. EP241126a: GSP detects optical counterpart
  11. EP241126a: TRT optical counterpart detection
  12. EP241126a: EP detection of a fast X-ray transient
  13. GRB 241113B: EP-FXT afterglow detection
  14. Konus-Wind detection of GRB 241115D / EP 241115a
  15. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  16. EP241125a: Optical upper limit with Kinder observations
  17. EP241125a: EP detection of an X-ray transient
  18. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  19. GRB 241113B: SVOM/VT optical afterglow observations
  20. Konus-Wind detection of GRB 241117A
  21. GRB 241025A: VIRT Optical Upper Limit
  22. Konus-Wind detection of GRB 241120A
  23. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  24. EP-WXT trigger 01709018832: Lick/Kast spectroscopy with the 3 m Shane telescope
  25. EP241119a: Optical upper limits with Kinder observations
  26. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  27. EP241119a: GIT optical upper limits
  28. EP241119a : J-band observations with WINTER
  29. EP241119a: Global MASTER-Net observations report
  30. EP241119a: EP detection of a fast X-ray transient
  31. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  32. GRB 241113B: Mephisto upper limits
  33. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  34. GRB 241115D / EP 241115a: SVOM/GRM observation
  35. The EP-WXT trigger 01709120856 is likely a flaring star
  36. EP241115a: Global MASTER-Net observations report
  37. EP241115a: EP detection of a fast X-ray transient
  38. EP241113a: No Detection in Fermi-GBM Observations
  39. EP 241113a: LBT possible optical counterpart
  40. GRB 241113B: KAIT Optical Afterglow Candidate
  41. EP241113a: Global MASTER-Net observations report
  42. EP241113a : J-band observations with WINTER
  43. EP241113b: Global MASTER-Net observations report
  44. EP241113b/GRB 241113B: EP detection of GRB 241113B
  45. EP241113a: EP on-board trigger and autonomous follow-up observation
  46. Konus-Wind detection of GRB 241107A (short/hard)
  47. EP241107a: EP-FXT follow-up observations
  48. GRB 241025A: VZLUSAT-2 detection
  49. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  50. EP241109a: confirmation of a stellar flare by BOOTES-7
  51. EP241109a: EP on-board trigger and autonomous follow-up observation
  52. EP241107A: MASTER optical observations of xray transient
  53. EP241107a: Kinder optical follow-up observations
  54. GRB 241104A: CALET Gamma-Ray Burst Monitor detection
  55. EP241107a: AKO Optical Afterglow Follow-Up Observations
  56. EP241107a: GSP detects optical counterpart
  57. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  58. GRB 241105A: EP-FXT follow-up observations
  59. EP241107a: GIT optical observations
  60. EP241107a: Global MASTER-Net observations report
  61. EP241107a: SVOM/C-GFT optical observations
  62. EP241107a: AKO Optical Afterglow Detection
  63. EP241107a: EP on-board trigger and autonomous follow-up observation
  64. EP241101a: CrAO ZTSH optical observations
  65. Konus-Wind detection of GRB 241105A (short with extended emission)
  66. Konus-Wind detection of GRB 241021A
  67. GRB 241104A: Swift-XRT observations
  68. GRB 241104A: Fermi GBM Observation
  69. GRB 241104A/EP241104a: Optical upper limits with Kinder observations
  70. GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
  71. EP241104a: EP detection of GRB 241104A X-ray emission
  72. EP241101a: EP-FXT observations update
  73. EP241103a: GOTO optical upper limit
  74. EP241101a: Possible detection of an optical counterpart with FTW
  75. EP241103a: Swift XRT detection and improved X-ray position
  76. EP241101a: Optical upper limits with Kinder observations
  77. EP241103a: Gemini optical limits
  78. EP241103a: EP observation update
  79. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  80. EP241103a: GSP optical upper limit
  81. EP241103A: LCO optical observations
  82. EP241103a: Global MASTER-Net observations report
  83. EP241103a: an X-ray transient detected by Einstein Probe
  84. EP241101a: Global MASTER-Net observations report
  85. EP241101a: BOOTES-7 optical upper limit
  86. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  87. EP241101a: EP-WXT detection of a fast X-ray transient
  88. EP241021a: Upper limit from Konus-Wind observations
  89. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  90. EP EP241030a: Global MASTER-Net observations report
  91. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  92. EP241021a: Swift-UVOT detection
  93. Konus-Wind detection of GRB 241030A
  94. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  95. EP241026b: EP-FXT follow-up observation
  96. EP241021a: ATCA radio observations
  97. EP 241026b: LBT possible optical counterpart (brightening source)
  98. GRB 241026A: the 100th GRB detected by GRBAlpha
  99. Konus-Wind detection of GRB 241025A
  100. GRB 241026A: GECAM detection

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