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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"

32494 results found.

  1. EP241021a: SOAR observations of the optical counterpart
  2. EP241021a: further SAO RAS optical observations
  3. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  4. EP 241026b: LBT optical observations
  5. EP241021a: e-MERLIN radio observation
  6. EP EP241026b: Global MASTER-Net observations report
  7. GRB 241026A: KAIT optical observations
  8. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  9. GRB 241026A: SAO RAS observations of possible optical afterglow
  10. Fermi GRB 241026A: Global MASTER-Net observations report
  11. GRB241025A: 1.3m DFOT optical afterglow detection
  12. EP241021a: optical follow-up observations with Xinglong Observatory
  13. ​GRB 241025A: optical photometry from Konkoly
  14. GRB 241025A: GROWTH-India Telescope optical observations
  15. GRB 241025A: COLIBRÍ Detection of the Afterglow
  16. GRB 241025C: Fermi GBM Detection
  17. GRB 241025A: Fermi GBM Observation
  18. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  19. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  20. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  21. EP 241021a: Swift-XRT observations
  22. EP241021a: optical follow-up observations with the Liverpool Telescope
  23. Fermi GRB 241025A: Global MASTER-Net observations report
  24. Swift GRB 241025A: Global MASTER-Net observations report
  25. EP241025a (GRB 241025A): EP observations update
  26. GRB 241025A : SVOM/VT optical afterglow observations
  27. EP 241021A: Swift ToO observations
  28. EP241021a: Liverpool Telescope optical follow-up observations
  29. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  30. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  31. GRB 241025A: DDOTI Afterglow detection
  32. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  33. GRB 241025A: SVOM/GRM observation
  34. GRB 241025A: TRT optical afterglow observation
  35. Fermi GRB 241024B: Global MASTER-Net observations report
  36. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  37. GRB 241001A: ATCA radio observations
  38. EP241021a: No Detection in Fermi-GBM Observation
  39. GRB 241010A: VIRT Optical Upper Limit
  40. EP241021a: VLT/FORS2 redshift z = 0.75
  41. EP241021a: SAO RAS optical observations
  42. EP241021a: KAIT optical observations
  43. EP241021a: EP-FXT follow-up observation update
  44. IPN triangulation of GRB 241021A (long)
  45. EP241021a: Optical counterpart observations with the Liverpool Telescope
  46. EP241021a: 1.3m DFOT Optical observations
  47. EP241021a: GSP detects optical candidate counterpart
  48. EP241021a: Optical upper limits with Kinder observations
  49. EP241021a: TRT optical observations
  50. GRB 241018A: SVOM/C-GFT optical observations
  51. EP241021a: NOT likely optical counterpart
  52. EP EP241021a: Global MASTER-Net observations report
  53. GRB241017A: 1.3m DFOT optical upper limit
  54. GRB 241018A: 1.3m DFOT Optical upper limit
  55. GRB 241018A: EP-FXT afterglow detection
  56. EP241021a: GOTO optical upper limits
  57. Konus-Wind detection of GRB 241018A
  58. GRB 241018A: SVOM/GRM observation
  59. GRB 241018A/sb24101802: Mephisto optical upper limit
  60. GRB 241017A/sb24101702: Mephisto optical upper limit
  61. GRB 241018A: Mondy optical upper limit
  62. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  63. GRB 241018A: GROWTH-India telescope optical upper limit
  64. GRB241018A: XingLong Optical Upper Limit
  65. GRB 241018A: REM optical/NIR upper limits
  66. GRB 241018A: NOT optical observations
  67. GRB 241017A: SVOM/VT follow-up and optical upper limit
  68. GRB 241018A: SVOM/VT follow-up and optical candidate
  69. GRB 241018A: LCO/0.4m optical upper limits
  70. GRB 241018A: Swift ToO observations
  71. GRB 241006A: VIRT Optical Upper Limit
  72. GRB 240727A: VIRT Optical Upper Limit
  73. GRB 241018A: X-ray afterglow candidate observed by MXT
  74. GRB 241016B: Fermi GBM Observations
  75. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  76. GRB 241001A: EP-FXT afterglow detection
  77. GRB 241017A: GROWTH-India Telescope optical upper limit
  78. GRB241017A: TOO Observations by SVOM/MXT
  79. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  80. GRB 241017A: J-band upper limit from WINTER
  81. GRB 241016B: SVOM/GRM observation
  82. GRB 241017A: Swift ToO observations
  83. Fermi GRB 241016B: Global MASTER-Net observations report
  84. Fermi GRB 241016A: Global MASTER-Net observations report
  85. GRB 241010A: Swift-BAT refined analysis
  86. GRB 241013B: Fermi GBM Observation
  87. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  88. GRB 241013A: Fermi GBM Observation
  89. GRB 240916A: radio detection with the VLA
  90. GRB241013A: REM observations
  91. GRB 241009A: LCO optical upper limits
  92. GRB 241013B: SVOM/GRM observation
  93. Fermi GRB 241013B: Global MASTER-Net observations report
  94. GRB 241013A: a long GRB detected by INTEGRAL
  95. LIGO/Virgo/KAGRA S241009em: Updated Sky localization
  96. LIGO/Virgo/KAGRA S241011k: Updated Sky localization
  97. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  98. Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
  99. GRB 241009A: GRANDMA optical upper limits
  100. GRB 241010A: JinShan optical observations and potential host galaxy

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