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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
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28108 results found.

  1. GRB 250804B: SVOM/GRM observation of a short burst
  2. GRB 250804A: Fermi GBM Final Localization
  3. EP250802a: additional Liverpool Telescope upper limits
  4. EP250730a: SVOM/VT optical upper limit
  5. EP250802a: Liverpool Telescope optical upper limits
  6. EP250802a: Global MASTER-Net observations report
  7. EP250802a: GROWTH-India Telescope optical upper limit
  8. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  9. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  11. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  12. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  13. EP250711a: CrAO and Assy optical observations
  14. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  15. EP250730a: COLIBRÍ optical upper limit
  16. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  17. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  18. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  19. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  20. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  22. GRB 250727A: EP-FXT follow-up observation
  23. GRB 250725A: PRIME near-infrared observations
  24. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  25. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  26. GRB 250728A: Swift-XRT observations
  27. GRB 250728A: COLIBRÍ optical upper limit
  28. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  29. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  30. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  31. GRB 250727A: EP-FXT counterpart detection
  32. GRB 250727A: Swift-XRT observations
  33. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  35. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  36. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  37. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  38. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  39. GRB 250725A: Swift-XRT refined Analysis
  40. GRB 250725A: Fermi GBM Observation
  41. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  42. GRB 250725A: Swift-BAT refined analysis
  43. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  44. GRB 250725A: SVOM/GRM observation
  45. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  46. GRB 250725A: Swift/UVOT Upper Limits
  47. GRB 250725A: Fermi-LAT detection
  48. GRB 250725A: BOOTES-7 early optical detection
  49. GRB 250725A: SVOM/VT optical candidate
  50. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  51. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  53. GRB 250725A: Enhanced Swift-XRT position
  54. GRB 250725A: Swift detection of a burst
  55. Swift GRB 250725A: Global MASTER-Net OT detection
  56. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  57. SVOM J195836+32283 is not a real source
  58. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  59. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  60. GRB 250721A: Fermi GBM Observation
  61. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  62. GRB 250721A: Swift-XRT observations
  63. GRB 250717B: SVOM/GRM observation
  64. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  65. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  66. GRB 250721A: MAXI/GSC detection
  67. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  68. GRB 250717B: COLIBRÍ optical upper limit
  69. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  70. GRB 250717B: Swift-XRT observations
  71. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  72. Swift GRB250718.01: Global MASTER-Net observations report
  73. GRB 270713A: Kitab and AbAO Optical Observations
  74. GRB 250717B: Fermi GBM Observation
  75. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  76. GRB 250716A: Swift-XRT afterglow detection
  77. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  78. GRB 250716A: Fermi GBM Observation
  79. GRB 250714A: SVOM/GRM observation
  80. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  81. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  82. GRB 250713A: Mephisto optical upper limits
  83. GRB 250713A: SVOM/VT optical upper limit
  84. GRB 250713A: NOT optical upper limits
  85. GRB 250713A: OHP/T193 upper limit
  86. GRB 250713A: SVOM/C-GFT upper limit
  87. GRB 250706B/C: 7DT Follow-up Observations
  88. GRB 250713A: Swift-XRT observations
  89. GRB 250713A: EP-FXT counterpart detection
  90. EP250711a: COLIBRÍ continuous optical observations
  91. GRB 250706A: Swift-BAT refined analysis
  92. GRB 250702F: Swift-BAT refined analysis
  93. GRB 250628A: Swift-BAT refined analysis
  94. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  95. GRB 250713A: JinShan optical upper limits
  96. GRB 250713A: SVOM detection of a long burst
  97. EP250711a: Global MASTER-Net observations report
  98. GRB 250711A: DDOTI Optical Upper Limit
  99. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  100. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate

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