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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"
  1. EP241107a: Global MASTER-Net observations report
  2. EP241107a: SVOM/C-GFT optical observations
  3. EP241107a: AKO Optical Afterglow Detection
  4. GRB 241025A: LBT optical observations
  5. GRB241105A: Gemini-South Optical Afterglow Detection
  6. EP241107a: EP on-board trigger and autonomous follow-up observation
  7. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  8. GRB 241105A: Swift/UVOT Detection
  9. EP241101a: CrAO ZTSH optical observations
  10. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  11. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  12. GRB 241105A: BOOTES-7 optical detection
  13. GRB 241030A: Mondy optical observations
  14. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  15. Konus-Wind detection of GRB 241105A (short with extended emission)
  16. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  17. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  18. Konus-Wind detection of GRB 241021A
  19. GRB 241105A: SVOM/VT optical afterglow observations
  20. GRB 241105A: Swift-XRT afterglow detection
  21. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  22. GRB 241104A: Swift-XRT observations
  23. GRB 240511A: LCO upper limits
  24. GRB 241104A: Fermi GBM Observation
  25. GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source
  26. GRB 241105A: Swift ToO observations
  27. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  28. GRB 241104A: Swift ToO observations
  29. GRB 241104A: NOT optical non-detection
  30. GRB 241105A: GOTO tentative optical counterpart candidate
  31. Fermi GRB 241105A: Global MASTER-Net observations report
  32. GRB 241104A: SVOM/VT optical candidate
  33. GRB 241105A: Fermi GBM Final Real-time Localization
  34. GRB 241104A/EP241104a: Optical upper limits with Kinder observations
  35. GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
  36. GRB 241104A: SVOM/GRM observation
  37. EP241104a: EP detection of GRB 241104A X-ray emission
  38. GRB 241010A: host galaxy redshift z = 0.977
  39. EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
  40. GRB 241104A : Detection and localization by SVOM/ECLAIRs
  41. GRB 240821A: further radio observations with the VLA
  42. Fermi GRB 241104A: Global MASTER-Net observations report
  43. GRB 241104A: Fermi GBM Final Real-time Localization
  44. GRB 241030A: GRBAlpha detection
  45. EP241101a: EP-FXT observations update
  46. EP241103a: GIT optical upper limit
  47. EP241021a: OHP/T193 further optical observations
  48. LIGO/Virgo/KAGRA S241104a: Retraction of GW compact binary merger candidate
  49. Fermi trigger No 752365806: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  51. LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
  52. EP241103a: GOTO optical upper limit
  53. LIGO/Virgo/KAGRA S241102br: Updated Sky localization
  54. EP241101a: Possible detection of an optical counterpart with FTW
  55. EP241103a: Swift XRT detection and improved X-ray position
  56. EP241021a: continued SOAR observations
  57. EP241101a: Optical upper limits with Kinder observations
  58. EP241101a: OHP/T193 optical observations
  59. EP241103a: Gemini optical limits
  60. EP241103a: EP observation update
  61. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  62. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  63. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  64. EP241103a: GSP optical upper limit
  65. EP241103A: LCO optical observations
  66. EP241103a: Global MASTER-Net observations report
  67. EP241103a: an X-ray transient detected by Einstein Probe
  68. GRB 241030A: Rapid release of TESS data.
  69. EP241101a: Global MASTER-Net observations report
  70. GRB 241029A: GRBAlpha detection
  71. EP241101a: BOOTES-7 optical upper limit
  72. LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
  73. S241102cy: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S241102br: NED Galaxies in the Localization Volume
  75. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  76. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  77. GRB241030A: OHP/T193 optical observations
  78. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  79. EP241101a: EP-WXT detection of a fast X-ray transient
  80. Swift GRB 241101A: Global MASTER-Net observations report
  81. GRB 241101A: FRAM-ORM optical limit
  82. LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
  83. GRB 241030A/EP241030a: TNOT observations of the optical counterpart
  84. EP241021a: Upper limit from Konus-Wind observations
  85. GRB 241101A: Swift-BAT refined analysis
  86. GRB 241030A: further SAO RAS optical observations
  87. GRB 241030A: Optical Observations via Virtual Telescope Project
  88. EP241021a: Liverpool Telescope optical follow-up observations
  89. GRB 241030B: Swift-XRT refined Analysis
  90. GRB 241026A: SAO RAS optical observations
  91. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  92. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  93. GRB 241101A: Swift detection of a burst
  94. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits (duplicate submission of 38023)
  95. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
  96. EP241021a: OHP/T193 optical observations
  97. GRB 241030A: Palomar 1-m telescope COSMOS optical observations
  98. GRB 241030B: Montarrenti Observatory optical upper limit
  99. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  100. EP241026b: Liverpool Telescope optical follow-up

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