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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

1095 results found.

  1. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  2. EP251221a: Einstein Probe detection of a fast X-ray transient
  3. EP251220a: EP-FXT follow-up observation
  4. EP251220a: EP detection of a fast X-ray transient
  5. EP251214a: Optical upper limit with Kinder observations
  6. GRB 251202A: radio detection with the VLA
  7. EP251214b : Einstein Probe detection of a fast X-ray transient
  8. EP251214b : Einstein Probe detection of a fast X-ray transient
  9. EP251214a: EP-FXT non-detection and upper limit
  10. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  11. EP251212a / GRB 251212A: AstroSat CZTI detection
  12. EP251212a: EP-FXT follow-up observation
  13. EP251212a: Einstein Probe detection of an X-ray transient
  14. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  15. The EP-WXT trigger 01709249380 is likely a flaring star
  16. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  17. GRB 251202A: SVOM/GRM observation
  18. GRB 251203C: EP-FXT follow-up observation
  19. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  20. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  21. EP251202a / GRB251202A: AstroSat CZTI detection
  22. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  23. GRB 251202A: Fermi GBM Observation
  24. GRB 251202A: GOTO optical afterglow detection
  25. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  26. GRB 251202A: Swift-XRT afterglow detection
  27. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  28. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  29. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  30. EP251130a: Optical detections with Kinder observations
  31. EP251130A: Optical observation from 1.3m DFOT
  32. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  33. EP251130a: Swift-XRT counterpart detection
  34. EP251130a: Einstein Probe detection of an X-ray transient
  35. EP251129a/GRB 251129A: EP-FXT follow-up observations
  36. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  37. GRB 251129A / EP251129a: SAO RAS optical observations
  38. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  39. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  40. EP251124b follow-up observation by EP-FXT
  41. EP251124b: EP-WXT detection of a fast X-ray transient
  42. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  43. EP251124a: Swift-XRT observations
  44. EP251124a: Optical upper limit with Kinder observations
  45. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  46. EP251124a: Einstein Probe detection of an X-ray transient
  47. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  48. The EP-WXT trigger 01709248783 is likely a flaring star
  49. EP251118A: 3.6m DOT optical afterglow detection
  50. GRB 251122A / EP251122a: EP-FXT counterpart detection
  51. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  52. GRB 251122A / EP251122a: WFST optical observations
  53. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  54. EP251122a: Einstein Probe detection of an X-ray transient
  55. EP251118a: Continued Optical Detection with Kinder observations
  56. The EP-WXT trigger 01709248635 is likely a flaring star
  57. EP251118A: 1.3m DFOT optical afterglow detection
  58. EP251118a / GRB 251118C: SAO RAS optical observations
  59. EP251118a: Optical detection with Kinder observations
  60. The EP-WXT trigger 01709248403 is likely a flaring star
  61. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  62. The EP-WXT trigger 01709248388 is likely a flaring star
  63. EP251118a: preliminary result of EP-FXT follow-up observation
  64. EP251118a: NOT candidate optical counterpart
  65. EP251118a: Einstein Probe detected of a fast X-ray transient
  66. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  67. GRB 251116B: EP-FXT follow-up observation
  68. The EP-WXT trigger 01709248221 is likely a flaring star
  69. GRB 251111A: Swift-XRT observations
  70. GRB 251111A: EP-FXT counterpart detection
  71. The EP-WXT trigger 01709248051 is likely a flaring star
  72. EP251102a: update of EP-FXT follow-up observation
  73. EP251102a: Einstein Probe detection of a fast X-ray transient
  74. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  75. GRB 251026A/EP251026a: EP-FXT follow-up observation
  76. The EP-WXT trigger 01709247588 is likely a flaring star
  77. The EP-WXT trigger 01709247525 is not a real source
  78. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  79. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  80. GRB 251023B: Glowbug gamma-ray detection
  81. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  82. EP#01709247298: Swift-XRT counterpart detection
  83. EP251023a: Einstein Probe detection of an X-ray transient
  84. EP/WXT 01709247295: GOTO optical afterglow candidate.
  85. EP251021b: BOOTES-7 optical upper limit
  86. EP251021b: Einstein Probe detection of a fast X-ray transient
  87. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  88. GRB 251013C: EP-FXT counterpart detection
  89. GRB 251006B: Fermi GBM Observation
  90. GRB 251006B/EP251006a: EP-FXT afterglow detection
  91. GRB 251006B/EP251006a: EP-FXT follow-up observation
  92. GRB 251006B/EP251006a: EP-WXT detection
  93. EP251003a: Einstein Probe detection of an X-ray transient
  94. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  95. GRB 251002A: EP-FXT counterpart detection
  96. GRB 250925A/EP250925a: EP-WXT detection
  97. GRB 250919A: Glowbug gamma-ray detection
  98. GRB 250919A: Swift-XRT afterglow detection
  99. EP250919a: Einstein Probe detection of an X-ray transient
  100. The EP-WXT trigger 01709243841: Las Cumbres discovery of the optical counterpart

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