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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"

24368 results found.

  1. EP250802a: EP-FXT follow-up observation
  2. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  3. EP250806a: SVOM /VT optical candidate
  4. GRB 250805A: Swift-BAT refined analysis
  5. GRB 250806A: SVOM/VT refined analysis
  6. GRB 250806A: SVOM detection of a soft burst
  7. GRB 250805A: SVOM/VT optical counterpart
  8. GRB 250804B: Swift-XRT observations
  9. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 250805A: Swift detection of a burst
  11. Swift GRB250805.26: Global MASTER-Net observations report
  12. Fermi trigger No 776041355: Global MASTER-Net observations report
  13. GRB 250804B: SVOM/GRM observation of a short burst
  14. GRB 250804A: Fermi GBM Final Localization
  15. EP250730a: SVOM/VT optical upper limit
  16. EP250802a: Global MASTER-Net observations report
  17. EP250802a: GROWTH-India Telescope optical upper limit
  18. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  19. The EP-WXT trigger 01709198251 is likely a flaring star
  20. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  21. The EP-WXT trigger 01709198202 is likely a flaring star
  22. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  23. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  24. EP250730a: Global MASTER-Net observations report
  25. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  26. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  27. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  28. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  29. GRB 250727A: EP-FXT follow-up observation
  30. GRB: Clarification on Gamma-Ray Burst Naming Convention
  31. GRB 250728A: Swift-XRT observations
  32. GRB 250727A: SVOM/ECLAIRs refined analysis
  33. GRB 250728A: Fermi GBM Observation
  34. Fermi trigger No 775387550: Global MASTER-Net observations report
  35. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  36. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  37. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  38. GRB 250727A: EP-FXT counterpart detection
  39. GRB250727A: SVOM/VT optical upper limit
  40. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  42. GRB 250727A: SVOM detection of a burst
  43. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  44. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  45. The EP-WXT trigger 01709195487 is likely a flaring star
  46. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  47. GRB 250725A: Fermi GBM Observation
  48. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  49. GRB 250725A: Swift-BAT refined analysis
  50. Konus-Wind detection of GRB 250725A
  51. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  52. GRB 250725A: SVOM/GRM observation
  53. GRB 250725A: Fermi-LAT detection
  54. GRB 250725A: BOOTES-7 early optical detection
  55. GRB 250725A: SVOM/VT optical candidate
  56. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  57. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  59. Swift GRB 250725A: Global MASTER-Net OT detection
  60. GRB 250725A: Fermi GBM Final Real-time Localization
  61. Fermi GRB 250725A: Global MASTER-Net observations report
  62. Swift GRB 250725A: Global MASTER-Net observations report
  63. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  64. SVOM J195836+32283 is not a real source
  65. SVOM J195836+32283/sb25072103: Second VT observation
  66. GRB 250723B: Fermi GBM Final Real-time Localization
  67. GRB 250721A: Fermi GBM Observation
  68. GRB 250723A: Fermi GBM Final Real-time Localization
  69. GRB 250721A: Swift-XRT observations
  70. GRB 250722A: Fermi GBM Final Real-time Localization
  71. GRB 250713A : SVOM/ECLAIRs refined analysis
  72. GRB 250717B: SVOM/GRM observation
  73. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  74. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  75. GRB 250721A: Fermi GBM Final Localization
  76. GRB 250720B: Fermi GBM Final Localization Correction
  77. GRB 250720A: Fermi GBM Final Localization
  78. Fermi trigger No 774730635: Global MASTER-Net observations report
  79. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  80. GRB 250717B: COLIBRÍ optical upper limit
  81. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  82. GRB 250717B: Swift-XRT observations
  83. GRB 250718B: Fermi GBM Final Localization Correction
  84. GRB 250718B: Fermi GBM Final Real-time Localization
  85. Swift GRB250718.01: Global MASTER-Net observations report
  86. GRB 270713A: Kitab and AbAO Optical Observations
  87. GRB 250717B: Fermi GBM Observation
  88. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  89. Konus-Wind detection of GRB 250716A
  90. GRB 250717B: Fermi GBM Final Real-time Localization
  91. GRB 250717A: Fermi GBM Final Real-time Localization
  92. GRB 250716A: GOTO tentative optical counterpart candidate
  93. GRB 250716A: Fermi GBM Observation
  94. Fermi GRB 250716A: Global MASTER-Net observations report
  95. GRB 250716A: Fermi GBM Final Real-time Localization
  96. Fermi GRB 250715A: Global MASTER-Net observations report
  97. GRB 250715A: Fermi GBM Final Real-time Localization
  98. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  99. GRB 250713A: Mephisto optical upper limits
  100. Fermi GRB 250714A: Global MASTER-Net observations report

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