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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"

32510 results found.

  1. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  2. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  3. GRB241030A: OHP/T193 optical observations
  4. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  5. Swift GRB 241101A: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
  7. GRB 241030A/EP241030a: TNOT observations of the optical counterpart
  8. EP241021a: Upper limit from Konus-Wind observations
  9. GRB 241101A: Swift-BAT refined analysis
  10. GRB 241030A: further SAO RAS optical observations
  11. GRB 241030A: Optical Observations via Virtual Telescope Project
  12. EP241021a: Liverpool Telescope optical follow-up observations
  13. GRB 241026A: SAO RAS optical observations
  14. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  15. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  16. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits (duplicate submission of 38023)
  17. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
  18. EP241021a: OHP/T193 optical observations
  19. GRB 241030A: Palomar 1-m telescope COSMOS optical observations
  20. GRB 241030B: Montarrenti Observatory optical upper limit
  21. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  22. EP241026b: Liverpool Telescope optical follow-up
  23. GRB 241030A: SAO RAS optical observations
  24. GRB 241030A: Fermi GBM Observation
  25. EP241021a: AMI-LA radio detection
  26. GRB 241030B : GIT optical upper limits
  27. GRB 241030B: LCOGT Optical Upper Limits
  28. GRB 241030B: Swift-BAT refined analysis
  29. GRB 241030A: Swift-BAT refined analysis
  30. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  31. GRB 241030B: Swift/UVOT Detection
  32. EP EP241030a: Global MASTER-Net observations report
  33. GRB 241029A: LCO optical detection
  34. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  35. GRB 241030B: SVOM/GRM observation
  36. GRB 241030B : MITSuME Akeno optical upper limits
  37. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  38. GRB 241030B: SVOM/VT optical afterglow observations
  39. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  40. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  41. GRB241030B: Fermi GBM Observation
  42. GRB 241030B: BTA observations
  43. GRB 241029A: SVOM/VT optical afterglow observations
  44. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  45. GRB 241030B: optical observations from the INAF Asiago Observatory
  46. EP241021a: Swift-UVOT detection
  47. GRB241030B: GRANDMA/TAROT Upper Limit
  48. GRB 241030B: SAO RAS optical observations
  49. GRB 241030B: AKO Optical Afterglow Detection
  50. GRB 241030B: Nanshan/HMT optical afterglow detection
  51. GRB 241030B: SVOM/ECLAIRs detection of a burst
  52. Konus-Wind detection of GRB 241030A
  53. GRB 241030A: Fermi-LAT detection
  54. GRB 240912A: radio detection with the VLA
  55. Fermi GRB 241030A: Global MASTER-Net observations report
  56. GRB 241030A: AKO Optical Afterglow Detection
  57. Swift GRB 241030A: Global MASTER-Net observations report
  58. GRB 241030A: Swift/UVOT Detection
  59. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  60. GRB 241030A: SVOM/GRM observation
  61. GRB 241026A: Swift-BAT refined analysis
  62. GRB 241030A: SVOM/C-GFT optical observations
  63. GRB 241026A: LBT optical observations
  64. EP241021a: Optical rebrightening observations with Mephisto
  65. EP241026b: EP-FXT follow-up observation
  66. GRB 241030A: Multiband optical detection with Mephisto
  67. GRB 241030A: SVOM/VT optical afterglow observations
  68. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  69. GRB 241030A : MITSuME Akeno optical afterglow detection
  70. GRB 241029A: GROWTH-India Telescope optical follow up
  71. GRB 241030A: TRT optical observations
  72. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  73. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  74. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  75. GRB 241029A: SAO RAS optical observations
  76. GRB 241026A: SAO RAS optical observations
  77. EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
  78. EP241021a: SAO RAS observations of rebrightening
  79. GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
  80. EP241021a: ATCA radio observations
  81. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  82. GRB 241026A: Swift/UVOT Upper Limits
  83. GRB 241029A: Swift-XRT observations
  84. GRB 241029A: Fermi GBM Observation
  85. GRB 241029A: AKO Optical Afterglow Detection
  86. GRB 241029A: GOTO optical afterglow detection
  87. EP241021a: continued SOAR observations confirm optical rebrightening
  88. GRB 241029A: MASTER early optical counterpart detection
  89. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  90. GRB 241029A: Mephisto observations
  91. EP 241026b: LBT possible optical counterpart (brightening source)
  92. GRB 241029A: TRT optical afterglow candidate detection
  93. GRB 241029A: Swift ToO observations
  94. GRB 241029A: SVOM/GRM observation
  95. GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
  96. GRB 240821A: Keck/LRIS spectroscopic observations
  97. EP241021a: Gemini-South detection of optical rebrightening
  98. GRB 241026A: the 100th GRB detected by GRBAlpha
  99. GRB 241026A: TNOT optical counterpart detection
  100. Konus-Wind detection of GRB 241025A

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